PD - prope discoverer is an Unreal Engine-based game for iPhone and iPad that has players exploring a 3D castle environment to find three hidden cards in each area to unlock doors. It's sort of a hidden-object game, but with first-person movement and a fully rendered 3D world.
Prope Discoverer is definitely a mellower experience than Infinity Blade, but it's interesting to see a small Japanese company developing a first-person Unreal-based experience on iPhone. If you want to walk around the "idyllic sunlit gardens" and "eerie and bewildering castle cellars," you can download it for $3. Wander past the break for a trailer.