I don't know what you mean by "great", but I believe you'll have to adjust your expectations accordingly. I've been owning a 2015 1.2 Macbook for about 3 months now. I had the chance to test a bunch of Steam games on it. On paper, the Intel HD 5300 scores about 900 3DMark 11, which is a bit better than an Intel HD 4000. Back in 2012, I've owned a Macbook Air with an Intel HD 4000. I could manage to play Call of Duty MW3 quite smoothly on it. Fast forward 2016, the Intel HD 5300 struggled to maintain similar performance. I've found out that the HD 5300 from the 2015 Macbook throttles back a lot, due to heat. Throttling is much more aggressive than a Macbook Air. So, the final result is not pretty. Basically, my Macbook 2015 can sustain the max GPU frequency (1 GHz) for about two minutes. Then, it throttles back to about 40 % frequency (400 MHz) and remains there.
Some games that are playable (30 fps averable at 720p) would be: Call of Duty MW1 (high), Bioshock 1 (high), Bioshock 2 (medium), Diablo 3 (low-medium). Even Skyrim struggles on "low" (about 20fps).
On the other hand, I've just received a 2016 Macbook. I'm going to test it extensively over the weeked, but the first few tests I've performed are much more promising. For instance, Skyrim runs at more than 30fps on high (720p) now. Hope it helps.
Exactly. That's almost unreal. Mind you, I have played Skyrim for a few minutes only. I'm going to test it more extensively over the weekend. I've installed Assassin's Creed IV also. If I could play it on "low", that would be great. Macbook is not a gaming machine. However, it's the device I'm carrying with me during my trips. It's so light and sleek that it doesn't bother me on a flight or on a train. Great little thing.
What I can suggest are indie 2D games. Games like Shovel Knight for example run on my old 2008 MacBook decently, so I assume on the 2015 one it will run buttery smooth on high settings. Of course, this is just an assumption.