Geograph Seal is an FPS/platformer developed and published by Exact in 1994 for the Sharp X68000 computer.
Plot
You control a mecha sent to destroy enemy facilities on planet WS090, and encounter opposition from their robots.
Legacy
Albeit obscure at the time, being exclusive to a niche Japan-only platform, Geograph Seal is now noted as perhaps the first FPS with true 3D graphics. Unlike earlier games like Wolfenstein 3D or Doom, which used sprites for enemies and objects, Geograph Seal used polygons for almost everything. Exact would soon return to this formula with the Jumping Flash! series for the PlayStation.