I had an idea for a unit, maybe a marine sniper unit. Enable it to act like a sub, in the fact that it is invisible until it attacks, and enable it to move after an attack. It could be a recon unit, with a defense penalty, since it is not meant for going toe-to-toe with enemy units, but have an attack bonus since it attacks from stealth it you want to use it for hit an run attacks. It would be dependant upon the eletronics technology.
here are some stats I thought it could have
movement = four
sight =6
special ability- move after attack.
defense penaly=??