Games Like FULL METAL COFFIN

A 3D co-op submarine simulator with up to 8 players, where you fight for control over newly discovered resources below the Antarctic. Taking place in flooded caverns deep below, you and your CREW will be tasked with operating a submarine to complete various missions. Your vessel is specialty built using the latest in material science, to withstand the unique conditions posed by this new environment. Due to the mineral rich waters, a layer of dense brine covers the lower section of the caverns. Dive your submarine into this brine layer for added stealth, to evade detection, or attempt a desperate escape 

Mine resources, unlock new interesting torpedo types, and deploy them in combat. Load them immediately, or store them for future use. Planning and forethought are essential to a decisive victory against all enemies in the frontier

Good coordination and communication are heavily rewarded. Work together with friends to operate your vessel smoothly. Form a command structure, or naturally fill in where needed. Ensure steady operation of your submarine, and dominate the enemy