Shattered Pixel Dungeon is an open-source traditional roguelike dungeon crawler with randomized levels and enemies, and hundreds of items to collect and use. It's based on the source code of Pixel Dungeon, by Watabou.
When in the Geomancer's room, he will immediately start using his abilities and attacking the player. When the player mines through the rocks and attacks the Geomancer, the message "Make sure you're ready before you continue!" is printed, although the fight has already begun.
Reproduction:
When in the Geomancer's room, he will immediately start using his abilities and attacking the player. When the player mines through the rocks and attacks the Geomancer, the message "Make sure you're ready before you continue!" is printed, although the fight has already begun.