The objective is to destroy the enemy fort. The game features a campaign mode that serves as a tutorial and contains somewhat scripted scenarios, a skirmish mode that lacks random maps, a more freeform sandbox mode, and online multplayer. Once the enemy reactor is destroyed, you win. Each structure may be made out of wood or armor, with doors and ropes offering other options. Metal (collected from mines) and energy (collected from wind turbines) are used to build everything in the game, including defensive shields and sandbags. The workshop, factory, and upgrade center unlock new weapons. Those weapons include machine guns (primarily used for defense), mortars, snipers, missiles, cannons, and lasers. Since machine guns automatically fire at incoming projectiles, getting past the line of defense is tough (snipers are intended to take out machine gun emplacements). Offensive weapons must be manually fired in real time, which takes away from base building too much; you also cannot set a weapon to continually fire at a specific power and trajectory, increasing the micromanagement. Any damage can be repaired by simply holding down the “R” key and moving the mouse around; this process is too quick and results in rapid recovery before a fatal blow can be levelled. Thus, most games drag out far too long. The physics are plausible and the AI is generally a skilled opponent. Forts is a fine concept, but a number of shortcomings in gameplay (defensive advantages, repetitive aiming, fast repair) hold back ultimate enjoyment.