The Precursors is well worth a look. The ground portion uses Deus Ex-style FPS combat (hits are accuracy-based rather than dice rolls). There is a full weight-based inventory system, and you can modify weapons with different upgrades and ammo types; in addition to the usual assault rifles and the like there is also a bizarre array of living weapons found on the jungle planet (one of them is reloaded by feeding it live spiders, for instance). There are also various vehicles to drive including mechs, VTOL pods and Yoshi-like dinosaur things.
In space you have the expected combat and trading mechanics. You can upgrade your ship to be more powerful, and both missiles and fuel have to be purchased; pirates and traders are randomly generated everywhere you go, and in the case of the traders you can offer to escort them to a safe location or demand protection money (resulting in fighting their escort). If you want to you can even destroy the trade ship after getting your protection money and then collect spilled goods with the tractor beam to sell at the next station. :D If the escort proves too powerful you can even pay the trader to stop attacking you. The space portion isn't quite as outstanding as Freespace 2 or the like but it has been very well thought out.
Rather than upgrading skills over time by putting skill points into them there are "Perks" that are either or off, but in many cases unlocking one will open up one or more other ones with the same or similar purpose. This simplified system works well because you can immediately see a big difference rather than just upgrading something by 5% over time.
The quest system is surprisingly complex; most quests have multiple solutions, and how you solve a quest can open up or close off other quests. There are also several points during the main quest where you are given you a choice of what to do next, and each of the two branches offered has a set of completely different quests before the two eventually meet up again. It's quite something.
White Gold: War in Paradise is the sequel to Boiling Point: Road to Hell and the sister title of The Precursors, sharing the same engine and mechanics (although you can't go into outer space, of course). While not as unique as The Precursors--after all, when did we last see a game with both on-foot FPS-RPG and space sim components?--it's certainly an interesting game and shares all the strengths of its sister.
Unfortunately there has been no further news of an official English release of either game, with the most recent news being that the Xbox 360 versions of both games have been cancelled
. Fortunately the unofficial translations for both games are now complete, and both games can be bought digitally for GOG-level prices (refer to this thread for details