Alter

Alter is a first-person puzzle game for Minetest. It may be considered a spiritual successor to Portal with its style of plain puzzle rooms, strange sci-fi mechanics used to solve the puzzles, parkour elements, and hostile nonhuman narrator controlling the puzzles.

Story
The player wakes up in a room with no exits. An unknown voice gives basic hints on how to solve the puzzles while making disparaging remarks about humans' intelligence as measured by the puzzles.

Gameplay
The game takes place inside of puzzle rooms. Each room is divided into two areas by an unbreakable glass barrier and each half acts as a mirror universe to the other. The player must reach and press a red button in order to complete the puzzle.

The room may contain immovable white boxes and movable blue boxes. Picking up a blue box and placing it against any surface works as in other Minetest games except that the blue box appears in the opposite half of the room, mirroring the position where it was placed. The player is given a limited number of potions, which transport one to the mirror area. Running out will lose the game.

Reception
Alter won first place in the 2021 Minetest Game Jam.