Fortune Crafter

In Fortune Crafter you start as simple dude. You have 2 item slots: one for melee weapon and one for ranged weapon. Every weapon in the game has 5 upgrade slots. Dring run you can find new weapons and new upgrades that can be installed on your weapons. After you found needed upgrade you can level up it as many times as you wish as long as you have enough orbs(local currency).

Most weapons also have special upgrade. It is preinstalled and has unique effect for every weapon, for example, in this game there is a weapon that allows you to ressurect enemies to fight for you, the most limiting factor for this weapon is the fact that ressurected units do not travel with you between rooms, maxing special upgrade of that weapon will remove this limit allowing you to raise an undead army that will tramle every enemy standing against you.

Every unit in the game is govered by the same rules, every enemy has these 2 item slots, every weapon used by any unit has these 5 upgrade slots. That makes possible some unique synergies, for exapmle every summoning weapon will copy its upgrades to summoned units.

The fact above also makes playable every unit in the game, you can even play as the boss as long as you find a way to do it (it is possible and quite easy). Since every unit is playable the game allows you to continue playing after death by joining as ally unit(as long as you have alive ally).

For better replayability every endgame boss defeated unlocks new starting weapon with unique effects and synergies.Local Coop
Fortunce Crafter allows local coop with up to 64 players (I couldn't test it with 64 players, but it should work). To join you need to touch any button on your gamepad, the game will connect you as random friendly unit(starting room has a lot of them), it means that you can even join in the middle of a run if your freind has summoning weapon.

If you tired of being friends with your friends you can activate one of the pvp modes. First of them will allow you to join as enemies in normal runs(Yes, you will control all bosses and even endgame bosses). Second pvp move will put all players in arena with some loot.General
Fortune Crafter trys not to limit players at all, it is possible to do pretty much anything. Legally created by me builds include shield that prevents damage completly, staff that full cleares room by one click, summoned crazy golem that roamed every room, instant freeze sword that could stun lock even endgame bosses. And I am sure it is possible to create something even funnier.