The most annoying feature?

[retrolinkx]

Devs not knowing where to put checkpoints.

I have seen this in too many games.

Let's say I'm playing a game where you have to kill 50 enemies in a small room, that has infinite spawns, run to an objective that is 400 meters away, being bombarded by fire, the ally's are staying back doing nothing, and then when I get within reach of the place I'm supposed to go, I die.

I dislike this very much.