NPD!
http://www.gamespot.com/articles/pc-and-xbox-one-exclusive-titanfall-is-the-top-selling-us-game-for-march/1100-6419066/The full list, encompassing physical retail only, is below:
1. Titanfall (XBO, PC) | Electronic Arts
2. inFAMOUS Second Son (PS4) | Sony (Corp)
3. South Park: The Stick Of Truth (360, PS3, PC) | Ubisoft
4. Call Of Duty: Ghosts (360, PS4, PS3, XBO, NWU, PC) | Activision Blizzard (Corp)
5. Dark Souls II (PS3, 360) | Namco Bandai Games (Corp)
6. Metal Gear Solid V: Ground Zeroes (PS4, XBO, PS3, 360) | Konami Digital Ent.
7. NBA 2K14 (360, PS4, PS3, XBO, PC) | Take 2 Interactive (Corp)
8. Final Fantasy X/X-2 HD Remaster (PS3, PSV) | Square Enix Inc (Corp)
9. The LEGO Movie Videogame (360, PS3, 3DS, NWU, XBO, PS4, PSV) | Warner Bros. Interactive
10. Minecraft (360) | Microsoft (Corp)
The top-selling PC game overall was Diablo III: Reaper of Souls expansion.
And Yoshi's New Island was the "the tenth highest-selling SKU for March 2014, but did not rank in the top ten when looking at title-level sales."