I played and completed Killzone: Mercenary on the Vita. Killzone: Shadowfall was one of the first games my son had when he first got a PS4, so I played it a little back then. It can't any worse than the Halo campaigns.
Finished up Halo Reach last night. It's got the best gameplay and level design so far, but the stories in all the games suck. I guess it's the online play that makes these games so popular because the campaigns don't come close to anything in the Gears of War franchise. I also find the cover-based gameplay in Gears more enjoyable and strategic.
Having said all that, we're starting Halo 4 this weekend.
Finished up Halo: ODST tonight and started Halo: Reach. ODST was by far the best one so far. I ended up buying Halo 5 for $5 during Microsoft's Spring Sale, so we have 4 and 5 to play once we're done with Reach.
I've been looking for years, but all of the previous versions released (Forever, Infinity Gene and Extreme) were not arcade accurate. The Switch got a version (Invincible Collection), but it never came out on the PlayStation or Xbox.