Call of Duty: Modern Warfare 3 should fulfill your unreal needs

Naw i'm actually kidding there! Personally there were a quite a few games that strongly reminded me of unreal in some ways, these games also proved to be my main inspiration for me whenever i fire up Unrealed.
Far-Cry (stay away from its sequel!): This game reminded me sooooo much of unreal, so many aspects seem to be similar, you're a lone hero stranded on an island, you fight mercenaries who inhabit the place to mine resources/experiment/whatever, even the way the game progresses reminds me of unreal, progression is linear but there's plenty of paths to take to your objectives, even the mutants later on remind me sooo much of unreal's foes. Oh and the endgame, its an anticlimax but it also reminded me of unreal
Risen: The premise is the same (well, crashland on an island sounds similar, right?), and gameplay wise it also has many similarities. You travel around and explore native villages, ancient ruins, jungles, the whole invasion and opressed theme, its very unreal-ish thematically.
Gothic 2 is a bit old, but the addon reminded me alot of unreal too.
The Longest Journey: Okay, its a point and click adventure, but you also end up stranded on a gorgeous alien world with similar medieval architecture, and you have to explore to find your way out of there, the sequel is in 3d and looks alot better though .
Tomb raider(series): some of the temple exploration maps remind me sooo much of unreal's temples, that's why!
S.t.a.l.k.e.r:.... uhm just because the game is semi-non linear with so much freedom to do things your own way, its a long singleplayer game.
Left 4 dead: okay this is a funny one, but if you're into unreal co-op, this is my second favorite co-op game after unreal co-op.
The Dig: Another point and click adventure, and also about being stranded on an alien world with no way of getting home.
Arguably
Gears of War COULD fit the criteria too, since its singleplayer/co-op and its made by Epic, but i haven't really played it to judge that.