Didnt have 4 much in memory (meaning it wasnt impactful to me) and 5 is also non-existant.
Infinite was meh though I like Cortanas replacement. She has good humor.
regenerating health, allowing for a smoother difficulty curve and easier time balancing for devs
online multiplayer
A-B tested a bunch of controls for console shooter control schemes going forward
Until halo right-stick to turn, ads to aim on screen was a common control mechanism.
As soon as it released regenerating health, the control scheme and online multiplayer became a must-have for AAA fps.
For PC it's basically just regenerating health, which was has proved to be a mixed blessing.