Hints for digging: never dig steeper than 75 degrees, 70 is about optimal. Only hit dynamite from the side and not too close, this prevents you from getting stuck. This is helpful even if you have already surfaced, since it can save energy in navigation later on. When looking for rare items, space out the tunnels but be mindful of where they can be connected.
Too difficult! It's possible to get one overdrive if you manage to hold a combo for quite long, but breaking the combo basically dooms you to fail soon after. You can't break even on energy until you're about 10 combo or so, in which case you're just a few seconds from losing most of the energy anyway. So I haven't been able to survive more than about 2 minutes, which is really a bit too short for a game of this type. I would definitely appreciate a more easy or casual mode just to enjoy the music.
Since this is an example of an almost-perfect game in its genre, I'll try to keep comments short. The good things: the game is simple, no critical hits, luck stats, puzzle elements etc., loot is very nicely balanced and dungeon generation is quite interesting. The whole regen mechanism is very different from normal and it keeps things fresh, but potions become very obsolete. The bad things: targeting is horrible, inventory space is too small (compare all the other games with 30+ inventory space!), and graphics get too confusing near the end. Things that could be added: skill trees (especially a respec option) and more endgame content (after the boss, getting the whole hero set is just a matter of grinding through 6 levels, and there's very little replay value).
It starts off so easy in the first 20 levels, just eliminate all the biggest numbers and combine the rest... and soon you're at Tricky 10, thinking "What have I done?!" It pretty much ends up trial and error, but it's the good kind, that you can actually realize that a failure to plan 15 moves ago got you trapped with a block in the wrong place!
The grind for 100% achievements is really slow at the end, where they're all two stars and you have to do them in sequence, where basically . Running 10k and then collecting 500 fuel cans makes it a really slow grind. Last three achievements? Kill 6 bosses, open 30 containers, stomp 30 bosses. That's 9 runs through Boss 1, and 2 runs through Boss 2. The game really needs to keep statistics and then clear achievements from there.
Too much grinding on levels where clearing the level relies on having just enough health/invincibility at the right point. There's no real difference between the enemies other than how much damage they do, and unless you have the ability to plan your damage so you survive with less than 10 health it doesn't even help to know that info. In short, the difficulty curve is too steep, and it needs more variety in upgrades and enemies. Try redesigning the game so that the optimal strategy is NOT just to stand in the center and go afk.
Game is quite good, but the player is confused throughout the first few minutes of play due to lack of explanation. I thought I was done after chapter 3, and had to reread the description to realize that there was more (!). The wording on the achievements page is confusing too. A bit of a tip to other players: drag tiles into the space below locked tiles, it helps to clear them.
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Updatet - Arrows for player 1