The title supports up to four players in every combination of couch and online co-op. However, there are only three classes, so a four player game will have two folks playing as either the mercenary, wizard or assassin. Actually, all four players can rock the same class if they'd like, but it's definitely better to have diversity of expertise on the field.
There is no skill tree or leveling in Crimson Alliance. Players acquire gear that increases their armor, which increases their health. "Leveling up" is all based on gear gathered from the "crafted" (i.e. pre-generated) dungeons and loot drops. It's also possible to purchase items in the store, but I didn't get to see that functionality in the demo.
Crimson Alliance feels fresh, yet familiar. It's a weird notion playing through a game and getting the impression that this should all be so tired by now, but something about it is compelling and different. You're doing the basics: killing massive waves of enemies, exploring the dungeon for secret nooks and grabbing all the gold in sight, but it's the little changes that make the difference.
An interesting feature is that as you kill enemies a multiplier starts ticking up. Conversely, if your character gets hit the multiplier starts ticking back down. At the end of the level the score goes toward a medal and is also converted to gold for use at the store. It helps to learn to block very early in this game if you're looking to get gold in the 18 available levels.
The gameplay consists of hacking and slashing your way through waves of minions, tossing exploding barrels, flinging throwing axes, dropping medieval turrets, flinging monster meat to distract the horde, using your class' ultimate ability and reviving fallen team members efficiently before you're also consumed by the monsters.
Crimson Alliance is the type of game that's made accessible and fun by scaling difficulty levels and going on the journey with friends. If you're looking for a game to play with friends, keep an eye on how Crimson Alliance is turning out. The game will be available later in the summer for an unannounced price.