Thanks for your thoughts everyone.
Shadowfury333: I read your post several times but I don't quite understand your "health trap". What gave you the idea of such a thing? I agree that a healing unit competes with caretakers.
sprang: I guess I don't yet understand your definition of interactivity.
Orphelius: a healing aura would have the added benefit of showing more clearly what happened. And if it were localised around the explosion (e.g. "a swarm of repair nanobots" or whatever") it would be an incentive to grab and hold that area until the effect fades. But some units already have self-healing capabilities. So an aura seems slightly out of place to me in the ZK universe.
Okay, let's play with the unit properties for the fun of it. Here are some variations on the concept that come to my mind:
- make it explode violently if killed by the enemy (e.g. Roach-like damaging explosion): nobody would take it to the front line and use it there because you don't place obvious time bombs next to your units.
- make it move really slowly so it cannot effectively retreat: then it's better and more efficient to move damaged units to the back to repair them, where caretakers and cons can do the same job in (relative) safety.
- bigger change: make it a support unit that simultaneously reclaims metal and repairs nearby units from the reclaimed metal at a high speed (separate from your normal metal economy). If it explodes, it leaves a healing aura where it was destroyed. That way, it's only useful during/after battles and only in areas with debris. Its high repair rate is the incentive for use, but it can be killed before it completes its job and would then potentially help the enemy for a while. What if this were a unit from the strider hub? Would that make it too expensive?
Some long-winded bonus story: the inspiration for that unit came while remembering the game Magicka. It's an excellent game focused on coop spellcasting where the spells of different players interact when cast. The results can be anything from suprisingly good to devastatingly bad. The hallmark of that game is that the stressful situation in which the spells need to be cast just generate total chaos, but in a fun way. For example: player A heals player B with a healing beam, player C fires an arcane beam at an opponent - crossing player A's healing beam. The resulting explosion kills player A. Ups. Luckily, the revive spell is the first one the game teaches you.
While such total chaos is obviously not appropriate in an RTS, I still like the concept of actions being able to backfire on the player in a surprising, slightly annoying, but not game-losing way. This healing unit was intended as a way to do just that.