This suggestion’s inspiration came from the game Deus Ex: Human Revolution. I am offering this as a possible solution to the issue of soldiers having to choose between carrying grenades or mines. Here are the basic steps outlined below of how this would work:
1.) Research/discover explosive mines. This unlocks Mine Templates – a lightweight, modular base that you can “equip” a grenade to.
2.) In inventory, whether at base or on the field, equip any grenade (explosive, flashbang, EMP, toxin, etc.) to a mine template. This creates a mine that functions just like that grenade.
3.) Equip the mine. Deploy it on a surface. When deploying, a prompt displays to allow you to set the detonation parameters – proximity, remote, or timed. Pick one. The mine is now armed.
If a mine is not necessary, a soldier can instead detach the grenade from the template and separate them into two parts again, thus freeing him to throw the grenade and still keep the mine template for later in case he gets another grenade to insert into it.
Possible other uses for mine templates:
a.) Research an upgrade to Mine Templates to give them mobility: wheels; tracks; or wall-climbing spider-legs. Mines created from inserted grenades now have the ability to move towards their targets. All-terrain versions could track them up walls and obstacles. Embedded hydraulics could even allow the mines to jump. Especially advanced tech could let them hover or FLY. Your choice!
…i) Early uses of drone technology could involve mine templates to create suicide drones, driven remotely by an operator via antenna.
b.) Mine templates could also be upgraded with a single-shot launcher system, to turn it into something more like an on-demand mortar shell bombardment. When the mine is triggered, the grenade would be launched in a steep vertical arc, clearing most obstacles, and come down to explode on enemies.
…i.) The extra flight time of “mortar” grenades means they are pretty ineffective at hitting enemies on the move, so they can’t be used as proximity weapons (unless they’re firing from under a roof).