Red Faction

The Grenades in Red Faction have 2 fire modes: Instant detonation (primary fire) and Time delayed (alt fire). Instant detonation is preferable so enemies don't have a chance to run away but watch where you throw them as their blast radius is quite large. You will likely have to go a bit out of your way for these kills, as they're slightly cumbersome to go for. There are more than enough grenades however so providing you go for them, you will have enough in a single playthrough.