Apparently, there's some debate as to whether the 2-state, 3-colour universal Turing machine is actually universal. I have assembled another version of this Turing machine, which implements the 2-state, 18-colour machine published by Yurii Rogozhin in 1996, but I haven't written out the details on the web yet. That version exchanges the roles of Teysa, Orzhov Scion and Rotlung Reanimator, so that rather than watching for dying creature tokens of specific colours, it would watch for dying creature tokens of specific creature types – and Magic has hundreds of creature types. It also uses Necroskitter as a way to avoid the fiddly mana payments required for the False Dawn-Skirk Drill Sergeant approach.
This was implemented as version 5 of the Turing machine, which went online on 25th September 2012.