Now, continuing the analogy with GZDoom, we can point to Chocolate Doom as a comparison. Chocolate Doom is a Doom source port that tries to recreate the experience of the original DOS Doom games, keeping the original code intact wherever possible and retaining the original behavior and look-and-feel, including bugs. The only changes are fixes to game-breaking bugs and improvements to quality-of-life aspects like controls remapping.
As for other ports of the Marathon engine, Old Durandal took a similar direction to Chocolate Doom (though it did expand the capabilities of the original engine a bit), but development seems to have petered out several years ago.
Given all of this, a couple of other community members and I are currently in the early stages of creating a Chocolate Doom-like port of Marathon. The working title of this project is Chocothon. At first, this would just be a port of the M2/Infinity engine, but a further goal would be to fork the code and create an engine that is an accurate reimplementation of Marathon 1, since no such thing currently exists. That portion of the project would obviously be a considerable undertaking, given that there is no source code release for M1, but the "anachronisms" folders tucked away in Infinity's source code release coupled with decompilation of the original PowerPC binary should give us enough clues to light the way on what needs to be changed. That's the hope, anyway.
High-level goals of the project would be:
- accurately reproduce the behavior of the original trilogy
- emulate the look-and-feel of the original games, including their menu interfaces
- fix major game-breaking bugs, like the bug in M2's engine which stops the game after 15 levels are finished in a row
- write a suite of tests for the engine code which ensures the behavior is not changed
- (eventually) provide an accurate reimplementation of Marathon 1
- running scenarios which are intended for Aleph One
- implementing hardware-accelerated renderers
- extending the capabilities of the original engines