The Contact grenade mode can be used within the Variable Grenade, available from "Atlas" onwards. After being thrown, it explodes when hitting any surface, similarly to the Mortar Round from previous games.
The Contact Grenade is available as an individual grenade in Exo Survival mode. It can be purchased from the armory, and it is shot with the Exo Launcher. It is also the default Exo Launcher for the Demolition class.
Contact grenades appear in Exo Zombies. They are generally very effective, due to the instant explosion, ability to cancel throwing the grenade, and the ability to purchase more grenades off the wall in the middle of the round (unlike the Fragmentation Grenades).