What's the point of having three heroes if they can't even help each other. It's stupid when you lose a level because one guy died while your two other guys have full health. There needs to be a way for lanes to help each other. There is just too much chance involved. It doesn't matter how buff your warrior is if you never get more than two red houses in a row. There needs to be a way to scramble the board.
For those having trouble getting gold on survival like I did, try building 5 flame towers on top of each other facing left on the far right as soon as you start. Slash away at the demons as they come, when the first one reaches a soft animal build another 5 flame towers facing right on the far left side. This combination should hold off everything for a while. Eventually you'll collect a huge number of souls and your regular sword attacks will do a ridiculous amount of damage, one or two shotting everything except bosses. The only thing you have to worry about is ghosts. If they come, just drop a quick eye block, kill the ghost, and sell the block.
Got all badges on first run through the game. I was chaos desert and white robe and focused completely on attack (no defense at all) upgraded only attack bolts at first. I learned the spells that give you bonus high and low bolts asap. While upgrading, I put some points into mana, enough to not run out in battles. It's ok to have low hp if you have enough attack bolts to block. I got high and clan magic every chance I got. Somewhere in the middle I maxed out basic damage. Eventually, I won every battle the same way. First two turns use only low and high bolts. Start adding the bonus high low bolts. If you have number of bolts, basic damage, and burning maxed out, a combination of all those spells can do a few thousand damage, enough to kill anyone in the game usually. By the end of the game, I had everything maxed out except for the defense and ended up with 420 health and 1010 mana. If anyone is planning on trying for all three badges in the first file, I hope this helps.
Advice for survival: learn to throw away weapons. There are weapons that the computer is awesome with and you suck with (i.e. the grenades and various guns). Pick them up before a computer does, run to the side of the screen and chuck it away by pressing d. Throw away whatever you think is potentially dangerous. Flamethrowers and ray guns will set the enemy on fire, during which they can set you on fire by touching you. And one last thing. Don't try to fight club your way through enemies. Do one quick punch and jump over them. Turn and repeat. Kicks are useless btw.
Finally got the hard badge. I did it on level 29. The strategy to level 14 is to build only crypts on everything. Build some towers on the mana pools and keep spamming cut out to get enough money to build more and upgrade your crypts. If your undead is leveled up enough, the evil ninja at the end should freeze or fear (and the odds are pretty good that he will), then screw him up with meteors. As for level 15, the strategy i used is to build temples on the top three high grounds and crypts on the lower three. Your main defense against those damn ninjas is a fully leveled up hellfire temple, which, if youre lucky, will hit even invisible ninjas when it fires on noninvisible ones. Throw a couple of dens on the bottom, and a few crypts at the top and you should beat level 15 on splendid pretty easily.
 "King's Guard"){kind=icon}
 "High Tea"){kind=icon}
 "Survival Lab"){kind=icon}
 "Topsy Turvy"){kind=icon}
 "You Find Yourself In A Room"){kind=icon}
 "Castaway"){kind=icon}
 "Papa's Burgeria"){kind=icon}
 "Neon Race"){kind=icon}
 "Epic Coaster"){kind=icon}
 "Doodle Devil"){kind=icon}
 "Demons Took My Daughter"){kind=icon}
 "Book of Mages: The Dark Times"){kind=icon}
 "Doodle God"){kind=icon}
 "Protector IV"){kind=icon}
 "Chaos Faction 2"){kind=icon}
 "Pixel Legions"){kind=icon}
 "The Final Death Wish"){kind=icon}
 "Snail"){kind=icon}
 "Cursed Treasure: Don't Touch My Gems!"){kind=icon}
 "SteamBirds"){kind=icon}