Outland

There is a nice guide by Auburok (with pictures showing where the marks are on the in-game map) over on x360a. The marks are listed in the order in which you will encouter them in the game:

http://www.xbox360achievements.org/forum/showthread.php?t=30...

The Marks of the Gods are hovering golden idols. There are forty-two in the game, so collecting ten is very easy. You can check your progress by clicking the back button to open the Player Statistics screen.

Here's a nice, comprehensive and well organized guide I used to find the marks. It's a PS3 guide, but it works for the 360.

http://www.ps3trophies.org/forum/outland/113185-marks-gods-g...

You'll get the Enthusiast achievement while going for: