If you have the Intel Integrated Graphics, your framerates won't be good on Crysis. You might just barely get 30FPS on the lowest possible settings. Most MacBooks have weak GPUs, so they aren't well suited to high end gaming. You can download GPU-Z to check which graphics chip your MacBook has.
I tested some games on my Lenovo Y470 lapto (1366x768 resolution) using the Intel HD 3000 instead of the nVidia GT 550m.
In the 2nd chapter of Crysis (Relic) I was able to get on average about 24FPS with everything set to low. Peak FPS was probably 28FPS and dipped as low as 15FPS. Generally playable as long as you are not charging your enemies with guns a blazing. But everyone know that final battle is a real resource hog. I would expect an average of less than 15FPS in that final battle, with dips into the mid single digits.
Fallout 3 is playable with a mix of low and medium graphics. But you need to install a modified D3D9.dll file since the game does not recognize Intel graphic cores. The dll was originally meant for Oblivion, so obviously you can also play that game as well.http://www.oldblivion.com/sm/index.php?topic=6928.0
I actually decided to replay Mass Effect 2 and all the DLCs by just using the Intel HD 3000 graphic core. The game is playable. That means Mass Effect 1 should be fine. Don't know about Mass Effect 3 since I have not bought it yet.
King's Bounty - Armored Princess is playable, but for some strange reason some of the gets corrupted on a 1366x768 resolution screen.
Cities XL 2012 is playable on low settings but the game is not very well optimized (only uses 1 core) and suffers from memory leak which causes the game to eventually lag no matter how powerful your system / laptop is. Yep, it even lags with the nVidia GT 550m eventually...