MechWarrior: Living Legends - A Crysis Total Conversion Mod (also known as MW:LL or MWLL) is an award-winning, fan-created, multiplayer mod, based in the BattleTech universe, and using CryEngine 2 as its engine; it is one of the few mods based on the BattleTech universe (and its supporting Intellectual property) to have been sanctioned by Microsoft - who currently (as of 2011) owns the rights to the Mechwarrior video-game franchise - and additionally received pre-SDK support and sanctioning directly from Crytek, producers of the games' engine.

On December 26, 2009, an open beta (version 0.1.0) was released via BitTorrent and other distribution methods. Because the project changes the play-style and feel of the game it is originally based on (Crysis and Crysis Warhead) so completely as to be unrecognizable in comparison, it is billed as a "full-conversion" mod, since little to no trace of the original game's art or play-style (besides the most basic menus seen when first loading the game) exists any longer within MW:LL.