The plans as described on /StarCraftSet have panned out, for the most part. I included Brood War units and techs for the sake of bulking out the set (and it's still too small).
Terran units are mostly red, but a little white and blue; Terran spells are in all five colours. I decided to make the Terran entries in the two manafixing cycles provide mainly red, and less efficiently white or blue. The Zerg and Protoss entries in those cycles were easier because those rares are squarely two-colour.
I'm undecided whether I want to use mythic rares or not. Under my policy of following current Wizards policies, I guess I should. The card list doesn't do that at the moment, but I've indicated potential candidates for promotion to mythic rarity should it exist.
I'm afraid I am using a few Alara-style coloured artifacts, though the cards wouldn't suffer much if you deleted the "Artifact" type. I could make one or two abilities fit their computer-game counterparts better if I made every mechanical unit an artifact creature, including those with pilots, but I don't want to do that. I've used "Artifact Creature" to mean either (a) completely mechanical creature with no biological pilot, or (b) mechanical creature with a pilot but cast for colourless mana (i.e. SCV).
There's a fairly high amount of flying in the set, and some reach outside of the colours that would usually get it, because I've tried to match both ground/air and which ground units can engage air units faithfully to the game. But I haven't made much effort to indicate which flying units have air-to-air, air-to-ground, or both, apart from on Guardian. I don't think any of this is a problem mechanically though, but it could be a slight balance problem because it means black has a lot of flyers.
I've tried to give Zerg a slight mechanical identity around playing lots of creatures (because, well, they're Zerg). Protoss have an obvious mechanical tie of all having shield, but I haven't provided any mechanical tie for Protoss or Terran apart from that. I'm up for suggestions though.
For each colour, I'm aiming for 7 commons, 6 uncommons, and 5 rares, for a total of 18 cards in each colour, making 90 monocoloured cards. There will be some amount of artifacts, lands, and multicolour cards, bringing the set size up to about 110 or 115. (Approximately 40 commons, 35 uncommons, and 30 rares.) This is a bit small even for a small set. (Coldsnap was 155 cards: 65 commons, 50 uncommons, and 40 rares.) I'd like to hear any thoughts people have for increasing the size of the set
Currently designed totals: White: 17: 7/7 commons, 5/6 uncommons, 5/5 rares - so need 1U - 4 common creatures, 1 uncommon creature, 5 rare creatures - need more uncommon creatures and fewer rare creatures Blue: 16: 7/7 commons, 5/6 uncommons, 4/5 rares - need 1U and 1R - 3 common creatures, 4 uncommon creatures, 3 rare creatures - too many creatures? Black: 18: 7/7 commons, 6/6 uncommons, 5/5 rares - done - 3 common creatures, 3 uncommon creatures, 2 rare creatures - reasonable, perhaps slightly low creature count Red: 14: 6/7 commons, 2 which could be C or U, 2/6 uncommons, 4/5 rares - need 1 C/U, 2 U, 1R - 2 common creatures, 2 C/U, 2 uncommon creatures, 3 rare creatures - need 1 more U/C creature, rest noncreatures Green: 16: 7/7 commons, 6/6 uncommons, 4/5 rares - need 1R - 4 common creatures, 4 uncommon creatures, 1 rare creature - need 1 rare creature and perhaps another Artifacts: 6: 1 common, 3 uncommons, 2 rares Multi: 2 commons, 1 rare Land: 3 which could be C or U - need to decide required breakdown by rarity
Not yet carded
Motivated by concepts or characters Some Zerg spell referring to "three target attacking creatures" (not "up to three") Aldaris - but no white rare slot left (could lose the Sarah Kerrigan card) Zeratul, blue rare (but I'm not allowed any more blue creatures; perhaps move a Terran to red) Alexei Stukov and General DuGalle? are probably lower priority than Aldaris Some more buildings could have cards: Spore Colony, Sunken Colony, Starport (artifact or blue enchantment giving creatures flying)
Motivated by mechanical needs White common lifegain Red common/uncommon land destruction Black common/uncommon discard
White
Common
Zealot, 2W Creature - Protoss Warrior, 3/2 Shield 1 (Prevent the first 1 of any damage that would be dealt to this)
Dragoon, 3W Creature - Protoss Warrior, 2/2 Shield 2 (Prevent the first 2 of any damage that would be dealt to this) Reach
Interceptor, W Artifact Creature - Protoss Ship, 1/1 Flying
Defensive Matrix, W Instant Target creature gets +0/+4 UEOT.
Lockdown, 2W Enchantment - Aura Enchanted creature can't attack or block and its activated abilities can't be played.
Liftoff, W Instant Prevent all damage that would be dealt to you this turn.
Uncommon
Scout, 3WW Creature - Protoss Soldier, 4/1 Flying Shield 2 (Prevent the first 2 of any damage that would be dealt to this)
Shield Battery, 1W Enchantment 4: Target creature with shield gains an additional shield 2. (Prevent an additional 2 of any damage that would be dealt to it.)
Stasis Field, 2W Instant Prevent all combat damage that would be dealt this turn. Tap all attacking or blocking creatures. They don't untap in their controllers' next untap steps.
Missile Turret, 1W Enchantment Whenever a creature with flying attacks you, Missile Turret deals 1 damage to it. 1: Target creature gain detector UEOT.
Psi Storm, 3WW Instant Psi Storm deals 3 damage to any number of target attacking or blocking creatures.
Rare
Archon, 4WW Creature - Protoss Elemental, 6/1 Reach Shield 4 (Prevent the first 4 of any damage that would be dealt to this) Splash 3 (When this creature deals non-splash damage to a creature, you may have it deal 3 damage to another target creature.)
Reaver, 4WW (candidate mythic) Artifact Creature - Protoss, 2/3 Shield 2 (Prevent the first 2 of any damage that would be dealt to this) (1): Reaver deals 1 damage to target creature blocking or blocked by Reaver. Activate this ability no more than 8 times per turn. (or) Artifact Creature - Protoss, 0/3 Shield 2 (Prevent the first 2 of any damage that would be dealt to this) (1): Reaver gets +1/+0 UEOT. Activate this ability no more than 8 times per turn. Splash 3 (When this creature deals non-splash damage to a creature, you may have it deal 3 damage to another target creature.)
Fenix, 2WW, 3/3 Rare Legendary Creature - Protoss Warrior Shield 1 (Prevent the first 1 of any damage that would be dealt to this) When Fenix is put into a graveyard from the battlefield, if it had no +1/+1 counters on it, return it to the battlefield with a +1/+1 counter on it and it gains reach.
Sarah Kerrigan, 3W, 2/2 Legendary Creature - Human Rogue 2: Kerrigan gains cloaking UEOT. 2, T: Kerrigan deals 2 damage to target attacking or blocking creature.
Tassadar, 3WW, 4/2 (candidate mythic) Legendary Creature - Protoss Cleric Shield 2 (Prevent the first 2 of any damage that would be dealt to this) When Tassadar attacks and isn't blocked, you may sacrifice it. If you do, exile two target permanents.
Blue
Common
Ghost, 1U Creature - Human Soldier, 1/1 1: Ghost gains cloaking UEOT. (It can't be blocked or targeted by creatures without detector.)
Observer, 2U Artifact Creature - Protoss, 0/1 Defender, flying, detector (this creature may block creatures with cloaking), cloaking (this creature can't be targeted or damaged by creatures without detector)
Corsair, 2U Creature - Protoss Soldier, 2/1 Flying, shield 1 (Prevent the first 1 of any damage that would be dealt to this) 3U, T: Target noncreature permanent loses all abilities except mana abilities UEOT.
Scanner Sweep, 1U Instant Creatures you control gain detector UEOT. (They may block and target creatures with cloaking.) Look at target player's hand. Draw a card.
EMP, 1UU Instant All creatures lose shield until end of turn. Counter all instant or sorcery spells.
Recall, 1U Instant Return any number of target creatures you control to their owners' hands.
Decoy Attack, UU Instant Return up to two target creatures to their owners' hands.
Uncommon
Feedback, 2UU (could be common) Instant Counter up to one target spell. Until end of turn, up to one target creature loses shield and its activated abilities can't be activated.
Dark Templar, 5U (could be common) Creature - Protoss Warrior, 4/2 Cloaking (This creature can't be blocked, targeted or damaged by creatures without detector) Shield 2 (Prevent the first 2 of any damage that would be dealt to this)
High Templar, 3U Creature - Protoss Cleric, 2/2 Shield 1 (Prevent the first 1 of any damage that would be dealt to this) 1U, T: Target creature you control gains shroud UEOT.
Wraith, 2UU Creature - Human Soldier, 3/2 Flying 2: Wraith gains cloaking UEOT. (It can't be blocked, targeted or damaged by creatures without detector.)
Science Vessel, 4U Creature - Human Advisor, 0/4 Flying, detector T: You may cast an instant or sorcery from your hand, with its cost reduced by up to 2.
Rare
Carrier, 5UU Creature - Protoss Soldier, 0/3 Flying, Shield 3 (Prevent the first 3 of any damage that would be dealt to this) 1: Carrier gets +1/+0 UEOT. Activate this ability no more than 8 times per turn.
Arbiter, 4U Creature - Protoss Advisor, 1/2 Flying, Shield 2 (Prevent the first 2 of any damage that would be dealt to this) Other creatures you control have cloaking. (They can't be blocked, targeted or damaged by creatures without detector.)
Dark Archon, 2UU Creature - Protoss Elemental, 0/2 Shield 3 (Prevent the first 3 of any damage that would be dealt to this) 3UU, T: Gain control of target creature. That creature's controller may discard a card. If he or she does, sacrifice Dark Archon.
Forge, 2UU Enchantment Protoss you control get +1/+1, have an additional shield 1, and have vigilance.
Black
Common
Zergling Swarm, 1B Creature - Zerg, 2/1 When ~ is put into a graveyard from the battlefield, reveal the top card of your library. If it's a creature card, put it into your hand.
Hydralisk, 2B Creature - Zerg, 2/2 First strike, reach
Mutalisk, 3B Creature - Zerg, 3/1 Flying Splash 1 (When this creature deals non-splash damage to a creature, you may have it deal 1 damage to another target creature.)
Unburrow, 1B Instant Creatures you control gain first strike UEOT.
Spawn Broodling, 2B Instant Destroy target nonartifact creature without flying. Put a 0/1 green Zerg token named Broodling creature token onto the battlefield.
Zerg Rush, B Sorcery Target opponent loses life equal to the number of creatures you control. If it's your fourth turn or earlier, that player loses twice that much life instead. (or add 1 to cost and make a cantrip)
Uncommon
Guardian, 4BB Creature - Zerg, 5/3 Flying, first strike Prevent all damage that Guardian would deal to creatures with flying.
Devourer, 3BB Creature - Zerg, 3/2 Flying Whenever Devourer blocks or is blocked by a creature with flying, put a -1/-1 counter on that creature.
Queen, 2B Creature - Zerg, 0/2 Flying When you cast a creature spell, you may draw a card.
Plague, 3BB Sorcery Creatures your opponents control get -0/-3 UEOT.
Irradiate, 1BB Enchantment - Aura At the beginning of your upkeep, put a -1/-1 counter on enchanted creature and up to one other target creature with the same controller.
Hatchery, B Enchantment At the beginning of your upkeep, reveal the top card of your library. If it's a creature card, lose 1 life and put it into your hand.
Rare
Infested Command Centre, 5B (could be uncommon) Artifact Cast Infested Command Centre only if you dealt damage to an opponent this turn or if you control an SCV. 1, T: Put a 3/1 black Zombie token onto the battlefield with "When this creature deals combat damage, sacrifice it."
Kerrigan, Queen of Blades, 4BB, 5/5 Legendary Creature - Human Zerg Rogue 2: Kerrigan gains cloaking UEOT. When Kerrigan deals combat damage to an opponent, destroy target creature that player controls and put a +1/+1 counter on Kerrigan.
Arcturus Mengsk, 1BB, 2/2 Legendary Creature - Human Rogue 2(u/r), T: Gain control of target creature UEOT. 2B, T: When target creature becomes tapped this turn, destroy it.
Evolution Chamber, 3BB Enchantment Zerg you control get +1/+1 and have lifelink.
Samir Duran, 2BB (candidate mythic) Planeswalker, 4 +3: Sacrifice a creature. You gain 3 life. -1: Exile target creature. Return it to the battlefield under its owner's control at EOT. -8: Search your library for any number of cards and exile them. Search your library for any number of cards, shuffle it, and put those cards on top in a random order.
Red
Common
Marine, R Creature - Human Soldier, 1/1 Reach (or: 2/1 reach for 1R)
Firebat, 2R Creature - Human Soldier, 2/2 Splash 1 (When this creature deals non-splash damage to a creature, you may have it deal 1 damage to another target creature.)
Flame Blast, 1R Instant Flame Blast deals 2 damage divided as you choose between any number of target creatures and/or players.
Siege Mode, 1R Enchantment - Aura Enchanted creature has defender and "2, T: This creature deals 2 damage to target creature."
Yamato Cannon, 4R Sorcery Yamato Cannon deals 5 damage to target creature or player.
Charon Booster, R Instant Target creature without flying blocking or blocked by a creature with flying gets +3/+0 and gains first strike UEOT.
Could be common or uncommon: Goliath, 3R, U/C Creature - Human Soldier, 3/2 Reach When Goliath blocks or becomes blocked by a creature with flying, Goliath gets +2/+0 UEOT.
Valkyrie, 3R, U/C Creature - Human Soldier, 2/3 Flying When Valkyrie attacks or blocks, it deals 1 damage to each creature with flying target player controls.
Uncommon
Vulture, 2R Creature - Human Rogue, 3/1 Vulture enters the battlefield with three mine counters on it. T, remove a mine counter from Vulture: Put a 0/2 Spider artifact creature token onto the battlefield with "Sacrifice this token: This token deals 2 damage to target creature without flying."
Siege Tank, 3RR Creature - Human Soldier, 4/2 2R, T: Siege Tank deals 2 damage to target creature or player. Splash 2 (When this creature deals non-splash damage to a creature, you may have it deal 2 damage to another target creature.)
Rare
Battlecruiser, 4RR Creature - Human Soldier, 5/5 Flying 4RR: Battlecruiser deals 5 damage to target creature or player.
Jim Raynor, 2R, 2/2 Legendary Creature - Human Soldier At the beginning of your combat step, you may pay 2. If you do, target opponent chooses any number of creatures he or she controls. Each of those creatures blocks if able this turn, and you choose how. Other creatures that player controls can't block this turn.
General Duke, 3RR Legendary Creature - Human Soldier, 7/7 Whenever a source deals damage to General Duke, that source's controller gains control of General Duke.
Nuke, no mana cost (candidate mythic) Sorcery Nuke is red. Suspend 1 – 2RRR. Nuke deals 6 damage to each creature and each player.
Green
Common
Zergling, G Creature - Zerg, 1/1 When you cast this, you may search your library for a card named Zergling and put it onto the battlefield.
Lurker, 3G Creature - Zerg, 3/3 Cloaking (This creature can't be blocked, targeted or damaged by creatures without detector) (or) Creature - Zerg, 0/3 2: Lurker gets +4/+0 and gains defender and cloaking (it can't be blocked, targeted or damaged by creatures without detector). Activate this ability only once per turn.
Broodling, 0 Creature - Zerg, 0/1 Broodling is green. Flash G: Broodling gets +1/+1 UEOT. Activate this ability only once per turn.
Stim Pack, G Instant Target creature you control gets +4/+0 UEOT. At end of combat, it gets -2/-2 UEOT.
Burrow, GG Instant Up to two target creatures without flying gain cloaking UEOT. (They can't be blocked, targeted or damaged by creatures without detector.)
Ensnare, G Instant Tap up to two target creatures.
Power of the Swarm, 1G Enchantment - Aura When enchanted creature attacks, it gets +X/+X, where X is the number of attacking creatures.
Uncommon
Scourge, G, U/C Creature - Zerg, 0/1 Flying Sacrifice Scourge: Scourge deals 5 damage divided as you choose between up to two target creatures with flying.
Ultralisk, 5GG Creature - Zerg, 6/8 Trample
Defiler, 3G Creature - Zerg, 1/4 Sacrifice a creature: Add one mana of any colour to your mana pool.
Overlord, 2G Creature - Zerg, 0/4 Flying, detector At the beginning of your first main phase, add G to your mana pool. Spend this mana only on creature spells.
Parasite, 1G Enchantment - Aura Enchanted creature's controller plays with his or her hand revealed. Creatures that player controls lose cloaking.
Creep, G Enchantment Creatures you control get +0/+1.
Rare
Adrenal Glands, 2G Enchantment Creatures you control get +1/+0.
Nydus Canal, 1G Enchantment 2G, return a creature you control to its owner's hand: put a creature card from your hand with converted mana cost less than or equal to the returned creature's converted mana cost onto the battlefield.
Torrasque, 3GGGG, 6/6 Legendary Creature - Zerg Trample Torrasque gets +1/+1 for each other creature you control.
The Overmind, 2GG Legendary Enchantment 2G: Put a 1/1 green Zerg token named Zergling onto the battlefield. 3G: Search your library for a Zerg creature card, reveal it, and put it into your hand. 4BB: Gain control of target Zerg. (This effect lasts indefinitely.)
Artifact
Common
SCV, 2 Artifact Creature - Human Worker, 1/1 T: Add R to your mana pool. 1, T: Add W or U to your mana pool.
Uncommon
Scanner Station, 2 Artifact 3: Look at target player's hand. Creatures you control gain detector UEOT. (They may block, target and damage creatures with cloaking.)
Photon Cannon, 4 Artifact 3, T or W, T: Photon Cannon deals 2 damage to target attacking or blocking creature. 1: Target creature gains detector UEOT.
Bunker, 5 Artifact T: Up to 4 target creatures without flying get +0/+3 until end of turn.
Rare
Psi Emitter, 4 Artifact 3, T: Reveal the top 2 cards of target player's library. You may put a creature card from among them onto the battlefield. Put the rest on the bottom of that player's library in any order.
Psi Disruptor, 6 (candidate mythic) Artifact 3: Target creature has no controller UEOT. (Nobody can attack or block with it or activate its abilities. The active player controls its triggered abilities.)
Multicolour
Common
Drone, (g/b) Creature - Zerg, 1/1 T: Add G or B to your mana pool. Return Drone to its owner's hand. (or) T: Add G or B to your mana pool. Drone deals 1 damage to you.
Probe, 1(w/u) Artifact Creature - Protoss, 1/1 T: Add W or U to your mana pool.
Rare
Armoury, 2(w/r)(w/r) Enchantment Humans you control get +1/+1 and have first strike.
Land
Could be common or uncommon: Assimilator Land Assimilator enters the battlefield tapped with three vespene counters on it. T, remove a vespene counter from Assimilator: Add W or U to your mana pool. T, remove two vespene counters from Assimilator: Add WW or UU to your mana pool. T: Add 1 to your mana pool. Activate this ability only if there are no vespene counters on Assimilator.
Extractor Land Extractor enters the battlefield tapped with three vespene counters on it. T, remove a vespene counter from Extractor: Add B or G to your mana pool. T, remove two vespene counters from Extractor: Add BB or GG to your mana pool. T: Add 1 to your mana pool. Activate this ability only if there are no vespene counters on Extractor.
Refinery Land Refinery enters the battlefield tapped with three vespene counters on it. T, remove a vespene counter from Extractor: Add R to your mana pool. T, remove two vespene counters from Refinery: Add RR or UW to your mana pool. T: Add 1 to your mana pool. Activate this ability only if there are no vespene counters on Refinery.