Super Depth (PC-98)

Super Depth is a freeware shoot-’em-up created by the dōjin circle Bio 100 % and published for the NEC PC-9801 on 10 August 1991. The player captains the self-proclaimed “Ultimate Hyper Battleship” Yamaboku through three looping sets of four fields—Sea, Air, Space and Boss—each with its own control quirks. In the sea phase you steam left-and-right and drop depth-charges on submarines shown on a sonar strip; in the air and space phases your guns shoot forward, and the final arena pits you against a huge carrier craft. Power-ups boost both you and the enemy’s aggression, giving the game its escalating intensity. The title won the 1st Free Software Grand Prize (Amusement Division) and circulated widely on a single FDI image before Bio 100 % re-issued an authentic Flash/Android port in 2011. A more traditional sequel, Super Depth 2 Finalty, followed in 1995.