This 2D fan made Halo de-make made by French Dobermann Software is short, but sweet enough to play.
This 2D side-scroller is good enough that it ends up being surprisingly fun. However, this game will only last you minutes with a short, uninteresting, straightforward campaign and stagnant multiplayer mode with no one to play with.
Gameplay is relatively easy even on Legendary. Off-screen enemy AI do not follow you even after combat. The game is heavily scripted. However, it is a good looking Game Maker game with sprites taken from the canned Halo Blood Covenant fan made 2D Halo game.
All in all, it's interesting to see fans make games based on their beloved franchises. Halo Zero is a solid game.