The Unholy Grail

This game uses the relatively unknown JACL engine, but it plays pretty well.

This game is a sleeper hit; I hadn't heard of it, but it's well-put-together. You are on a floating scientific base on a small island that has experienced a recent die-off of fish, and a loss of all juvenile population. You are brought in from the outside to what is essentially a military situation.

The game has espionage, science, etc. Some of the puzzles are unfair a bit, but the game responds well to things you attempt to do, and contains a number of action scenes.