Very cool!!
If I may humbly suggest, an "unlimited mode" (within the non-timed mode) could be great because a) it takes a while to up the limit before starting — I went from 100 to 400 and could have kept going, but +2 as the default addition upon winning at that point seems too small (given how easy it is to overshoot the goal due to combos), and b) stopping after your goal when you could keep going seems unfortunate.