The -ideally- final installment of a 2000s FPS series that already displayed in what direction the developer would go. In our reality, it is not only a splitting point for Bungie but also for Halo, as 343 decided to further build on this game isntead of going back to Halo 3.
The campaign is decent with an unusual approach to grittyness for the series that works in execution, but I have to say the story isn't one of the greats. The premise of fighting an already lost war is delivered really well but the actual writing can fall flat and characters are mostly archetypes with their best scene being their deaths.
Gameplay works for the singleplayer, although melee is ridiculous in this one. Sure, Spartan IIIs are weaker than the Master Chief, but being nearly one-hit by the elite's turbo speed punch is insane. Almost as banal as Halo 2.
The weaknesses of the gameplay really shine in the multiplayer. It is an unfun mess lacking the beauty of Halo 3's abilities while failing to balance maps around sprinting, jetpacks and the other recharging power abilities. Add bloom to the party and you have a shit experience.
It is saved by forge and custom games, where it has some nice additions resulting in more fun modes.
Firefight also makes a return here and I can't say its either better or worse than ODST, as both have their strengths and weaknesses. Both are a fun time but there are far better iterations on that concept outside of Halo.

This was a little different than I expected. It was described as a "walking sim" so I expected to be carried through a surreal world on a narrow path. Instead I was confronted with few immediate areas and a whole lot more puzzle solving, with the main goal of finding as many endings as possible. In those endings, you determine the fate of the world, from obliteration to immortality. Which pretty much sums up that these endings, and with that the game itself, is concerned with life, existence, reality. It doesn't go particularly deep with any, but takes a look at so much while having a charming sense of humor a lot of the time.
It was a really fun and nice time figuring out as much as I could, giving me a night of horror and existentialism, and it will stay in my memory. I only wish it had more to show because got damn do I love the aesthetic this goes for.