Bestiary

• Each era of the Hall has its own monsters. Your runs start with the first one.
• Every run you clear in an era counts toward its next monster. The bestiary shows it as a silhouette, with how many more clears it needs.
• A new monster joins the ones you have. A room still holds at most 4.
• Monsters you find stay in every later era. Clears in a later era still count toward an earlier era's monsters.
• Every run ends with a boss: a giant one of a monster you have found. The newest is the most likely, the oldest the least.
• Newer monsters turn up more in rooms near the boss, older ones near the entrance. It is a lean, not a rule.
• Older monsters get rarer as more join, but never disappear.
• A run keeps the monsters it started with.

• Slime: from your first run. Wanders about and hurts you if you walk into it.
• Rat: after 1 cleared runs. Sits grooming, then scurries off fast.
• Knight: after 3 cleared runs. Chases you round the blocks.
• Snake: after 8 cleared runs. Charges when it sees you ahead of it, and turns to face you when hit.
• Bat: after 15 cleared runs. Hangs, flits about, and swoops at you over the blocks.
• Shield knight: after 25 cleared runs. Slow, with a shield in front. Get behind it to hurt it.

Monsters that shoot back are next for the 8-bit era, then ones that split, hop, ambush you from the floor, or spawn more. Later eras get their own, and bosses with moves of their own.