Recently, I promised to add a couple more tank parts to the game, and now one of them is ready - retractable spikes. It's a reforge of regular spikes, causing significantly more damage to enemies. Another important difference from regular spikes is that retractable spikes consume energy to work in proportion to their number on the tank - which depends on the size of its chassis.
And I should probably mention some details of this parts type, since it seems that I've never done this before. Bumper-type parts are attached to the forepart of the tank and play an important role in its protection - they deal damage to enemies in range, grants bonuses to total tank health and armor. They also reduce damage from collisions with objects in attack mode.