Previously, in OS X Mavericks it worked to minimise games, or navigate through open apps with cmd+tab even if the game was opened in full screen but now you can't do that anymore. Pressing cmd+tab doesn't have any effect. Also I can't find any way to minimise the game.
I don't really know whether this problem is only for steam games or any other game, as I don't have any non-steam game.
In my experience it depends on the Game-programmer itself and has nothing to do with Steam, f.e. I recently bought 'Lords of Xulima' on Steam and the Game-Developer has disabled any Non-Fullscreen features.
Sometimes there is a trick though: With the game running, try pressing cmd+alt+esc. That will open the 'force quit'-window which then enables you to use cmd-tab.
Try it with your game.
CMD+H seems to work too.
Strangly CMD+Mdoes not do anything.
I have found following trick - pressed SHIFT-TAB (what just brought steam window over the game in full screen mode, without ability to switch to any other app: both ALT-TAB and desktop switch did not work) and then clicked on "Controller Configuration", what brought window with dialog that there is no controller attached but this time on a new desktop called "Steam" which properly handles ALT-TAB and Desktop Switch. This is on Sierra.
