osu!lazer is the open-source, next-generation client overhaul of the free-to-play rhythm game osu!, rewritten from scratch by Dean Herbert (ppy) and community contributors using the custom osu-framework. While retaining the core circle-clicking, taiko, catch, and mania gameplay rulesets of the 2007 original, osu!lazer introduces updated game mechanics, including slider end accuracy scoring, real-time score processing, cross-platform mobile parity, and a highly customizable user interface and HUD layout. Built to eventually replace the legacy stable client, osu!lazer features a built-in skin editor, an overhauled multiplayer architecture with custom room settings, extensive gameplay modifier customization, and native support across Windows, macOS, Linux, Android, and iOS. Player progression, beatmap downloads, and global leaderboards are integrated directly with the main osu! infrastructure.