There's an absolute metric fuckton of differences but it is still Halo so, yeah, if you've only played a couple of times then I can imagine you won't notice all that much.
few big ones:
-New 'armour abilities' give players special abilities with cooldowns like sprinting, jetpacks and invisibility.
- rebalanced weapons change the game massively
- new health / shield system (more like Halo: CE)
- New game modes
- Spartans and Elites are different: Elites are bigger, faster, regenerate health and have different abilities to Spartans.
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