Almost no-one has played King's Field. I don't care if it's on consoles, the series as a whole has far more interesting dungeons than any of the linear bore-fests of Skyrim.
Alice: Madness Returns
Alpha Protocol (hugely flawed but still a great game)
Serious Sam 3 (don't think the game sold very well - didn't even get into the top 5 on steam if I remember correctly)
Bionic Commando (the fully 3d version)
Hunted: Demons Forge was fantastic in coop (not so much single player)
Soldiers Of Anarchy,admit game is kinda buggy but allot of flaws are solved with patching.
... I take the lives of a few to protect the lives of many. I commit acts of war to preserve the greater peace. I take no joy in killing, but make no mistake; I'll do what needs to be done. Because it's my job. It's my duty. My name is Sam Fisher, and I am a Splinter Cell.
Also Battlezone and its sequal for similar reasons
Came here to mention Lead and Gold as well. Doesn't have as much meat on its bones as others in the genre, but it's a fun little number if you can wrangle up enough people to play together.
I'm tempted to suggest Blur, but I think it may have had an okay-ish number of people pick it up. Unfortunately it was not enough to save Bizarre Creations. Probably one of the funnest racers I've played in the last few years. Lots of challenges, things to unlock, and it was nice to have combat in the races without the game being a Mario Kart clone, or Wipeout game.
Hard Reset. It's Serious Sam set in a cyberpunk universe. Sure it's frustrating when the game lets a Gorilla loose in a corridor, or when you're running backwards from an enemy and get stuck on a random object, but it's still awesome.
Outdoor open environments? Vehicles? Friendly AI squadmates with actual personalities who you could order about? Large selection of tactical weapons? Genuinly non linear missions with genuinly different ways to approach them based on your playstyle? Stealth Missions?
BLARGH THIS WAS 1995 FOR GODS SAKE.
Probably the only game to come close is Battlezone in 1998 which ticks many of the same boxes Terra Nova did AND NO ONE PLAYED THAT EITHER, or the rather excellent sequal.
King of Dragon Pass.
And I'll add, diverse environment affecting gameplay - not just a little lighting here and there, if you went on a mission on a high-gravity world, your projectile weapons were pretty much useless. Bring a grenade launcher on a low-gravity moon and enjoy sniping towers from two km away - interesting plot, very detailed setting, and one of the kickassest soundtrack ever.
Damn, that needs a remake like right now. On ArmA2 or Crysis.
I loved Terra Nova, despite the cheesy FMV, and the blocky voxel sprites. What I liked was that your squadmates actually did what they were ordered to. (Except for your coward brother who would bug-out whenever he came under fire). I'd love a modern remake, keeping the mission design and gameplay intact, but using more modern visuals and a proper first-person aiming system.
The Chronicles of Riddick
Rise of Legends. Is was released unfinished during E3 and proceeded to bomb like no other. It sold like 20000 copies in the first months IIRC. What was Microsoft thinking?
The Rise of Nations gameplay model is fantastic and RoL was to it like Alpha Centauri is to Civilization. The IP is lost, last I heard Brian Reynolds himself didn't know who owns it. And now he's working at Zynga. At least Big Huge Games survived this megaflop.
I'd kill for a new Rise of Nations.