Space Trader: Merchant Marine

Space Trader: Merchant Marine is a trading simulation game released by Hermitworks Entertainment, and is the only id Tech 3 engine game commercially released after the engine became open source.

Gameplay
The objective is to become the master trader within the solar system by obtaining as much money as possible through trades. It also contains elements of a first person shooter as part of some missions.

The game provides multiple means to collect money, through a choice of trade, missions, or bounties.