Most of it is mouse control. You can use wasd to move in the dungeon, but basically everything else is just clicking.
The main difference routes can be seen if you go to the gallery in the menu. There's basically 2 splits in the paths, lasting 15 turns in the first fight (switch the the healing spear and target yourself and allies) vs losing determines if you stay a virgin until later. If you're a virgin there's a special scene when you unlock prostitution later, where you get more cash for selling it.
Later you infiltrate the slavers, and winning a boss fight sets you on the "pure" route which has brainwashing content. Losing puts you on the "chaos" route, which has more scenes IIRC, and a varrient (mostly just a few lines of text) if you're still a virgin at that point.
Otherwise most of the scenes are available in both routes, depending on if you lose fights (the desert worms, goblins, arena fights exc.) how slutty you go (letting the lust worm get to high), and if you want to stay a virgin.
There's also basically no real game over state, you'll get a scene and then get a hint on how to succeed and the choice to go back (usually at least, I don't recall any true endings that require a reload / restart).