Ship subsystems are critical to survival in the PC game FTL: Faster Than Light. Subsystems differ from systems because they don’t need to be powered by your reactor and manning a subsystem effectively increases the level of the subsystem by one rank. Instead of requiring reactor power, they are self powered and always have as much power as levels. The reason you can’t depower subsystems is because their benefits are a lot more vital. A damaged subsystem is usually as lethal as an unpowered shield. The following guide to ship subsystems in FTL: Faster Than Light will detail the value of each system in your quest to save the federation.
Piloting (Mandatory) – All ships have a piloting subsystem and it is easily the most important system in the game. While the system is unmanned, you can’t jump, your FTL does not charge, and you can’t evade any enemy attacks. This is so debilitating that you basically want to station a crew member in piloting at all times, no matter what else is occurring on your ship. An Engi crew member makes a great pilot because Engi are bad in fights and repair damage very quickly. A Rockman is also a good choice because you don’t really suffer the slow speed of the Rockman when it stays in one place all the time. If you need to swap out that crew member for any reason, always move another crew member into piloting before moving the other crew member out. Except for protecting this system from damage, there is almost no advantage to upgrading it.
Door System (60 Scrap) – Almost every ship in the game automatically has this system. When this system is damaged, you are unable to open or close doors, except when a crew member walks through one. Each level beyond the first increases the durability of the doors against enemy boarders. Either stationing a crew member in this room or buying one rank is particularly useful in the second half of the game when boarding parties become common. It is a good idea to upgrade this subsystem at least once, because being unable to open doors makes it incredibly difficult to control fires.
Sensors (40 Scrap) – A ship without sensors is practically flying blind. When your ship doesn’t have this system or when it is damaged, you can only see the rooms in your ship that your crew members are in. This can be devastating when you are under fire or being boarded, because you won’t be able to see fires, hull breaches, or enemy crew on your ship. The level 2 upgrade is amazing for sensors because it lets you see where all enemy crew are on the enemy ship. This lets you target anti-personnel weapons effectively as well as usefully teleport in your boarding parties. This should be a top priority for manning until you upgrade it.
Backup Battery (35 Scrap) – The biggest advantage of the backup battery is that manning it doesn’t increase its effectiveness. This subsystem gives you either two or four bars of power that lasts for 30 seconds when used and then cools down for 20 seconds. This is amazing when you are suddenly hit by a plasma storm. It also can be used to suddenly provide power to a reserve weapon. The main cost of the backup battery is that you can’t have it equipped at the same time as the other three subsystems, so something has to give. If you have to ditch a subsystem, your door system is probably your best bet.