Shadowless

when you kill the troll and the key falls into the pit, making it impossible to grab

I'm afraid I have to add my voice to the small chorus of people who are experiencing freezing issues. It doesn't seem to happen at any particular moment. I'm usually fighting something. It'll freeze for awhile, then pause itself, but not let me unpause. I'm in Chrome, if that's helpful at all. But it doesn't seem to be the page that's freezing, just the game itself. Strangely, I can still click the Armor Games link when this happens.

There's a lot of problems, with running keys stuck, lag when picking locks (either hitting the bomb or not taking input at all), as well as random freezes.

(vote this one instead due to full completion)
Pick upgrades based on the skill you get, not stats (you can get stats anywhere). Rogue - 30/50/75% chance to shoot two arrows. Warrior - 30/40/50% chance to stun with melee attack. Adventurer - Bat lvl 1/2/3 flies around killing enemies. Defender - absorb 15/50/70% of dmg as health when you block an attack. Bow with rogue + crit itemization seems to be the best. Crits do a wide range of dmg, i have seen up to x4 or maybe x5 dmg on a crit.

Theres no visible skill tree to see what skills I've unlocked from leveling up.