From In Pursuit of greed, a dos era shooter, which is available as freeware with source code for quite some time (http://www.redshadowsoftware.com/projects/greed ) is now a FreeaAscal port available (seems win32 focussed):
today a Master of Orion 1 clone, Remnants of the Precursors (worked on for many years) was released as open source into beta (content is NC freeware). It claims feature completness while polishing is missing, it seems the game can be completed. Source code and game is java 8 based. Eventually...
was thinking the same -
two games came to my mind, for once the award winning, Cart Life (public domain/open source/freeware)
second one, Soviet Unterzögersdorf, with 2 episodes (as far as I found freeware - source...
some weeks ago, the zzt tp5.5 source code seems was reconstructed binary exact with blessing of tim sweeny.
there is also some freepascal port with linux focus https://github.com/kristomu/linux-reconstruction-of-zzt/releases
DarkPlaces engine game Wrath:Aeon of Ruin has its source code on github since November 2019
indie game developer Blendo games just released the source code to flotilla on 10th anniversary. Zlib license, assets not included
update regarding the devilution reverse engineering project: they reached just feature completeness with version 1.0 (https://www.gog.com/forum/diablo/devilutionx_100_gamepad_and_60fps_happy_new_year/page1)
additionally they added: - FPS > 20fps unlocked, touchscreen support, upscaling, support...
more a historical artifact than a real porting opportunity:
it seems some month ago a DOS/Windows RTS game from the 90s was open sourced -> some kind of Polish warcraft 1 clone