For those frustrated with level 14, it is without doubt the hardest level to get a first place on. Level 15 is probably hardest to get all the gold coins on. The two hardest achievements are the one using Mr Whiffy and the one using Routemaster
Helpful comments at this point are almost worthless as they won't get enough up-votes, but here goes.
Don't underestimate technology. Unless you're going for a specific goal on a run (reaching new depth or an achievement), make sure to hit as many enemy structures as possible. The bonuses really add up in the late game
Contrary to Shadoron, I didn't find the boss a challenge at all with my level 30 max equip axeman. I echo Gmnish's advice in the top comments - go for an axeman and buy stones before facing the boss fight on every floor
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