Rocket League is proving way more popular than developer Psyonix ever expected.

The driving-and-soccer hybrid is this summer’s breakout gaming hit, and its success has even surprised the San Diego-based studio. Players numbers are so high that Psyonix has been struggling to keep things running smoothly.

“Demand was so much higher than we expected it to be,” Psyonix founder Dave Hagewood told Gamasutra. “We really needed to build a better system to handle all that load. Funny thing is, we build bigger systems for bigger companies all the time. We just didn’t expect to need something like that for this particular game.”

Rocket League is a great example of an innovative game idea becoming a big success, and it shows that bold ideas and sales can go hand-in-hand. Currently the top-selling game on the Steam digital store, it’s proving popular on PlayStation 4, too (where it’s one of July’s free games for PS Plus subscribers).

The decision to make a deal with Sony has been helpful in building a large Rocket League community in a short time frame, but those player numbers don’t really count as individual sales. Unsurprisingly, Hagewood wonders how things would have panned out if Psyonix had decided to sell Rocket League on PS4 at launch instead.

“You look at the amount of [PS4] downloads and you go, ‘Wow, that would have made a lot of money if we’d had even a tenth of that in paid sales,’” said Hagewood. “But we knew what we were doing when we made that deal. We knew that was a possibility.

“I’m a very patient person, and I’d rather build this brand and make it become a thing than make piles of cash. I look at it as a long-term strategy. Even if we have to wait until we make Rocket League 2 — if it’s become a thing, that’s the most important thing for me. That it becomes this phenomenon. That people realize we’ve been making this really cool game, and now everyone’s playing it.”