Modders can certainly make us do a double take regularly. Just look at all of the different variations of Super Mario 64 we have gotten in the last couple of years since they were able to decompile it and get better access to the engine and underlying code.

I love seeing these types of developments though. It answers the "what if" for some games. What if Mortal Kombat II was released on the NES, Atari 2600, 3DO, etc. Consoles that obviously were never financially viable to release a title like this on, at least by large companies, are ripe for fans to do it.

Retro gaming can be an absolutely magical place.