i beat it on the easiest difficulty. pretty fun but hard, even on easy. lots of enemies and they only get tougher as you go. seems like i was barely damaging them towards the end. plus just way too many to handle.
beat last boss with mostly just my drones and running around the room in a circle, lol.
had a ton of fun with this game, played it probably 15hs, unlocked all the characters.
Beat the game by myself some times (enough to unlock the last character, i think it was 4 times) and with a friend we play it from time to time using different combination of characters, although the game gets harder and harder the more players you have because you start sharing items and instead of being 1 super player, you end up having 2 semi-weak players. Some characters are too focused for coop as tanks or supports to be effective playing alone.
As soon as you unlock the bandit, use it. I think its the easiest character to beat the game play alone
You dont have to rush, and you dont have to stay too much in a lvl. You need to hurry to find all the loot you can as fast as possible.
Keep running while looking for chests, kill the enemies that spawn close to you but dont take too long.
Once you activate a teleport you have 90seconds of enemies spawning. You will need to kill all the enemies that are still alive when the countdown ends. They spawn near you so, in these 90 seconds you can still run to the chests that you didnt have enough money to open, enemies will spawn around so you should be able to pick up almost everything. Leave the chests that are too far away or that you know you will need too much time to get and return.
For the 1st couple of levels you should be able to beat each lvl in about 4 minutes or less (counting the 90secs of boss fight)
When you get to the last level, you are asked if you want to go to the boss or to do the 1st level again (the game will load another randomly created 1st level, with new chests, enemies will keep getting harder).
But there is a moment in which BOSSES respawn as if they were normal enemies, but you have 3 rows of items (and a lot of them picked up more than once, they stack), and you wont care anymore, you are god. The boss doesnt scale up (at least not too much), so you will kill it without any effort
I wish the dev would do something to fix coop, the way it is right now its harder playing coop than alone