There’s technically a reason.
The OG Xbox version made by Bungie was ported to PC by Gearbox back in the day, and the port made some changes to the game in the process. More visual than gameplay oriented changes, but purists will say they ruined the game. The Gearbox port is what they built Halo Anniversary (the Xbox 360 remaster) and the TMMC version off of.
Some good ones that are not yet mentioned
I’m presently replaying Command & Conquer Red Alert 3 and love it. The cast for the FMVs is all-star, the game itself is a super refined version of Red Alert 2 (itself an all-time classic) and the story has no bearing on the rest of the series so it can be played in isolation with no advance knowledge of C&C
Call of Duty 3, World at War, Black Ops 1, Modern Warfare 3, and Black Ops 3 all have local split screen Co-op as an option