No revenue estimate for GOG — its rating/review counts don't calibrate to sales the way Steam's do. Reviews and prices only.

Tunnel B1

Underground. Faster than fear. You have become one with your war machine. Flesh sears. Metal warps. Darkness enfolds you. The tunnel has swallowed you whole. It is alive with the instruments of death. Even the walls want to kill you. The speed hurts. Trigger finger blisters. But it's all you've got. Because the light at the end of the tunnel is a thermonuclear explosion. Enemy weapons scream death down the black corridors! Haunting light sourcing and scaling Lock, dodge, turn, fire! Tunnel sensors guard against surprise attacks! Nuclear tunnel explosions get real dangerous, real fast!