It looks like Oblivion is that "good" other developers realized they would never be able to come close to its 'beauty', so they decided to directly copy its environments. Just look at these articles:
http://www.gameplasma.com/limbo_of_the_lost_or_oblivion.html (original article, seems to be offline now, probably too much hits)
http://kotaku.com/5015674/cheeky-pc-adventure-game-accused-of-grand-theft-assets
http://www.neogaf.com/forum/showthread.php?t=310683 (a forum topic about it, but it contains much information and screenshots. Tt looks like they didn't simply rip-off oblivion, but every other game in the universe)
I really don't now if this is funny or sad...
http://www.gameplasma.com/limbo_of_the_lost_or_oblivion.html (original article, seems to be offline now, probably too much hits)
http://kotaku.com/5015674/cheeky-pc-adventure-game-accused-of-grand-theft-assets
http://www.neogaf.com/forum/showthread.php?t=310683 (a forum topic about it, but it contains much information and screenshots. Tt looks like they didn't simply rip-off oblivion, but every other game in the universe)
I really don't now if this is funny or sad...