Played the patched version, and the time feels just perfect now! You can offer a choice for players to keep going at the 10 minute mark if they want to play a bit more and still give them the prize when they lose. That will offer the 30+ minute option for anyone who wants the long playtime (just don't hide anything there, or they'll still feel obligated to do it). Game can also ramp things up faster now, like throwing multiple red slimes at the player since it won't be as devastating to lose. If you want to offer different dares in the future, you can even try very short modes like 3 minutes with an immediately high difficulty level.
A minor bug I noticed is that the damage numbers are sometimes wrong, the first mana bullet hit of the game shows 0.25 and the rest show 16. Upgrading it shows 18, but the tooltip promises 5 more damage. Later some attacks show 200+ and don't defeat the slime, while a hit that displays 6 does. Balance wise, the hex disk and talismans are a lot weaker than the other abilities.
Thanks for making the patch, I enjoyed the game in full and got the victory picture!