I just came back to a run in progress after a fairly long break and forgot if the current run is a challenge or not. Is there any way I can check that? I don't feel like continuing the run but I also don't want to forfeit a challenge run with this many floors done.
Challenge runs have a small icon in the same place you can find the hard mode icon if you're playing on hard mode. The crossed-out trophy icon indicates that you can't earn item unlocks or achievements, and can also be found on runs where you manually input a seed. So this icon won't be a 100% guarantee that you're on challenge mode, but it's as close as you're likely to get.