I wouldn't exactly say the Intel HD 4000 is more than capable of handling games, but it does offer good enough performance to play current games with low resolution with either low or medium quality graphics as long as the games are not too demanding.
I briefly had my hands on a laptop with an i5-3210m that has the HD 4000 and a resolution of 1600x900. I tested a couple of games on it before it left my hands. I found that Dragon Age was playable as well as Tomb Raider. However, Tomb Raider had some driver related graphics glitches. When looking at large streams of water rushing by in caves there would be "black holes" that simply floats on by. If the graphics were "life size" then those holes would range from between 2 feet to 4 feet in diameter. Not sure if updated Intel drivers corrected the issue. I played each game for roughly 45 minutes.
I attempted to play Mass Effect 3, but I was not able to get it up and running. I also did not have enough time to troubleshoot the issue. The games does run with the older Intel HD 3000 because I played the on my Lenovo IdeaPad Y470 with the nvidia GT 550m graphics chip deactivated. If ME3 can run on the Intel HD 3000, then it can run on the Intel HD 4000 which is around 30% more powerful. Like I said, I just didn't have the time to troubleshoot. For the hell of it I completed ME3 just using the Intel HD 3000.
I also tested Fallout 3 on the Intel HD 3000. Not too bad from what I remember. It was playable with a mix of low and medium graphic settings so the HD 4000 should be a problem for Fallout 3 and Fallout: New Vegas.
On a whim, I just recently tested Skyrim on the HD 3000 in response to a question regarding if it was playable on the Intel HD 4000. Skyrim is a bit demanding, but not as demanding as more recent games like Hitman: Absolution and Crysis 3. Overall, I did find the game to be playable, on more or less low settings. That means playing at 1280x760 resolution instead of 1366x768, no shadows, no anti-aliasing, basically everything set to low with the exception of textures quality which was set to "high". Using "medium" resulted in graphics that seem just too awful to look at since all the other graphic options were set to low as well.
Skyrim's ini file needed to be modded and that took a bit of time since I had to Google about what settings to change. It also means installing a mod to reduce the texture size, which is probably why I was able to set texture quality to high and didn't really notice much difference in performance. I tested / played long enough that my character made it to level 10.
Overall, based on my test, Skyim is playable on the intel HD 3000 and thus also on the Intel HD 4000 as long as you keep your expectations low. I was able to get between mid 20's to high 40's FPS after all the mods I've installed to improve performance and changes made to the ini file. But you must devote the time into modding the game.