I messed around with the free version of Wicked Lair, and got bored pretty quickly. The problem is lack of variety. All games of Wicked Lair are essentially the same, though you might try different mixes just because.
You’re an Evil Overlord building a dungeon under a town, but “building a dungeon” is a gross exaggeration since there’s no layout. Each level is a linear 3-spot corridor, where each spot can have a monster or a trap. Monsters come in Melee, Ranged, Patrol, Plunderer, Gatherer, and Invader varieties.
Melee and ranged are kind of obvious, though the ranged monsters often don’t support the melee monsters in front of them. They wander back and forth a bit, and if they’re not close enough, they don’t help.
Patrol monsters move from their origin level and seek out attacking adventurers. Plunderers move up to the town, grab money, and then go down to your lair and deliver it. Gatherer monsters create mana and then deliver it to your lair. Invader monsters move up to the town, do damage, and die. All three become less effective the more layers you’ve built, since they have more distance to travel.
“Invaders” are critical since you need to destroy the town to win. They die repeatedly, but like all monsters, they respawn on a timer after dying.
It’s mildly interesting, particularly since different dungeon layer types have restrictions on what special monsters you can buy. In the base game, only the Pit had Invaders, but you want Catacombs for Plunderers, and Growth (nature level) for Patrol. The full game offers more dungeon layer types, though I didn’t try those out.
The thing is, though, it’s not like a tower defense game with a variety of levels presenting different challenges. There are three adventurers: fighter, rogue, and sorceress. There are exactly 1 of each. When one dies, a timer starts to re-spawn them from the town. As time goes on, they get more powerful abilities, tank-focused for the fighter, DPS / stealth for the rogue, and DPS / healing for the sorceress.
Once you’ve beaten a difficulty level, you’ve seen all you’re going to see for that difficulty. Upping the difficulty doesn’t really change much, just how strong the heroes are and how many HP the town has.