I've never played Halo and I imagine this is nothing like it, but for a 2600 game this is actually quite good! Would have been really well received if released back then.
I've never played Halo so it isn't all that exciting for me. I couldn't find out how to shoot until I found out I had to go up to get the gun. Cool though, when I get my Pandora I'll put the rom on there.
I tested it in Little John Portable. Turns out that in said emulator, there's severe graphical glitching. On half of Master Chief goes to another half of the screen XD!