Just a thought - but I think it would add another layer to the gameplay if certain systems could be partially damaged in addition to being destroyed. It might increase the excitement of a battle, creating tense situations.
Some examples:
Engine: A crit (or other normal direct hit) could have some of the following effects:
- Reduced speed, perhaps even progressive so that eventually it seizes up. Perhaps accompanied with some grinding noise
- Fire: Not immediate death, but again progressive. It's gonna blow soon!
- Stall: Temporary and maybe even random once it's damaged
- Lost or destroyed leg: maybe the mech can't turn well in one direction or can't back up. Maybe at the less extreme level the mech just limps, making it a little harder to hold manual targeting while moving
- Arms: weapons mounted on arms lose alignment with targeting reticle.
- Fills with smoke - reduced vision
- Hud gets knocked out or blurs or otherwise isn't working 100%
- Intermittent control failure - or loss of ability to go in certain directions
- Lose a jump jet on one side - mech doesn't jump straight