Just have a few suggestions…
An Achievement for every chapter completion
Started a new game - You started a new game.
Finished the game - Completed the game on any difficulty.
Killed the Casserole - You blew up the casserole in the microwave.
Killed a marine - You encountered your first HECU Marine and killed him.
Became a Genocidest - You have 53,596 kills in total.
(Secret) Fail - Decline the G-Man’s offer without saving beforehand.