Which new extreme levels are coming in 2025?

The Hundred Line: Last Defense Academy
In mid-2025 Geometry Dash Lite the game received a free update (v1.1.1) adding a difficulty mode called “Extreme & Despair”. This mode cranks up enemy difficulty dramatically, making tactical battles much more challenging.

DevilzMu Extreme (MU Online / MU Extreme variation)
This game has been adding new extreme content in its “Seasons”. For instance:

Season 5 introduced improvements like new end-game challenge levels, item upgrades to +14 and +15, limit increases for character resets (up to reset 12), maps with higher-level monsters, etc.

In Season 6, there are boosted experience rates, monster life adjustments, etc., to make leveling and resetting more intense / faster.