It sounds like you're looking for Diamond Rush – the classic puzzle/action game from Gameloft – specifically the version that runs as a Java (JAR) game on 320x240 resolution phones (common in old Sony Ericsson, Nokia, Samsung, and LG feature phones).
Gameplay Features
Beyond the 40 main levels, there are elusive secret stages hidden throughout each world, often requiring the Mithril Vest or expert timing to access. Technical Details & How to Play Today Diamond Rush 320x240 Jar
If you want:
files. The "320x240" designation refers to the screen resolution, which was high-definition for its time. Resolution Aspect: It sounds like you're looking for Diamond Rush
While feature phones are extinct, the spirit of Diamond Rush lives on. Here is how to relive the magic in 2025: Tight Grid-Based Movement — Optimized for keypad controls
Optimized Performance: Despite the increased detail, the J2ME engine was remarkably efficient, ensuring the game ran at a consistent frame rate even on devices with limited RAM. Secret Rooms and Replayability