Mocha Doom is a Doom source port written in pure Java by Velktron (Maes). It is the first source port of Doom based on a managed language to reach functional status, unlike the STARK engine and DoomCott that came before it. It is also the first non-C/C++/Delphi port of Doom not to be based on virtualization or cross-compilation of the Doom source code, or on a recreation using a different engine, but is actually a manual, hand-optimized translation and adaptation of the original.