Level 20

Level 20 is a 2D pixel-art platform game about exploring 20 randomly generated levels. You play as a newly formed explorer searching for a way back to the surface and investigating a tracker signal from your brother, Big B, who disappeared near level 15 after an attack by a worm robot. Humanity has lived underground for 500 years to escape aggressive robots, sheltering in the Underground City at level 0; the planet’s surface lies beyond level 20, a level no explorer has reached.

Explore the levels

Use the teleport in the Underground City to enter the levels. Each level has a randomly drawn biome, and special constructions may also appear at random. You collect the number of energy cells required to activate the teleport, then survive for the indicated time while a robot horde attacks. When the timer ends, reach and activate the teleport machine.

At each level’s end, choose whether to return to the city and spend your cells on equipment improvements or continue to the next level, risking the cells you have gathered. Returning from an expedition restarts your progress from level 1. If your life reaches zero, you return to the city and lose all collected cells. An emergency device can also bring you back to the city, but destroys the cells so they cannot be reused.

Build and survive

Difficulty rises continuously while you explore, so lingering makes each level more dangerous. Robots keep appearing even after you have collected enough cells to activate the teleport. Use your plasma machine gun carefully, as it can run out of energy. You can build stairs to reach difficult places and break scenery blocks to open routes, though some areas cannot be destroyed, including the Underground City and first-encounter arenas for Guardian Robots.

Flying robots can bypass blocks, while Guardian Robots can break them. A robot that builds stairs creates a powerful explosion that can also be used against enemies. Laser cannons restrict movement, Red Alert Robots raise the difficulty bar when you approach them, and Purple Defense Robots shield Guardian Robots from defeat. Guardian Robots require different strategies. When you first encounter one on a level, it blocks teleportation until you defeat it; afterward, it can return to lower levels to hunt you. Defeating one earns you a medal of honor and changes the game, allowing it to appear on previous levels.

Cells and upgrades

Energy cells are the raw material used to maintain the Underground City’s essential defenses and to improve exploration equipment. There are three types. Teleportation machines, rebuilt from robots, allow quick travel but can move you only one level at a time; you need enough cells to advance or return home. Guardian Robots interfere with teleport signals, so defeating one allows its teleporter to be configured with a level-encrypted inhibitor and prevents that signal from disabling it again.

Spend collected cells with the Improvement Merchant to unlock branches of a skill tree, including special abilities that add new functions to your exploration gear. Lucky chests can provide extra benefits for continuing or multiply your collected cells. You can also change your appearance by speaking to the Costume Merchant.

The underground world

Humans formed exploration squads to gather cells and find a route back to the surface, but no one has reached level 20. Big B was the most successful, making it to level 15 before turning back because of an extremely aggressive worm robot. He later disappeared during a check near the Underground City, after the same kind of robot attacked; no robot had ever been seen at level 0 before his disappearance. A signal from Big B’s tracker at level 15 gives you a reason to investigate whether he is there.