Oceanhorn
Is a big game with lot of graphics.
Develop games in your browser. Powerful, performant & highly capable.
Currently playing XCom - Enemy Unknown on my Android Tablet. Very complet and smooth game (3.6 GB of download).
Time spent on it right now: 4 hours (only playing on my way to work and back home)
I'm not generally a big mobile gamer either, but I have spent a *lot* of time on Pixel Dungeon. It's an incredibly well-designed little game.
I have to second a few already
X-Com Enemy Unknown
Horn
Knights of the Old Republic
Grand Theft Auto Series
Galaxy On Fire 1/2
DemonHunter
Aralon
RavenSword
Bastion
Street Fighter 4
The Simpsons: Tapped out! ... has grown really big as well.
Not very much gameplay, but heaps of content!
In my opinion all AAA titles that have been "adapted" for mobile are super complex, but thats kinda obvious isn't it...?
I would have to say a big/complex game is `Beastie Bay` and `Game Dev Story`. I have beat them but it basically has infinite replay value. Or if you wanted a fps there is `Modern combat 4`. It's great but you will want a moga controller for it. If you are wanting a mmo `Order & Chaos Online` is the way to go. There is a pretty big player base and they constantly add new content.