ダッシュでレインボー！ ～暇つぶし最適ゲーム～ is a free Android game developed by River Field. The game allows players to control a character by tapping the left and right sides of the screen. Tapping the left side moves the character to the left, while tapping the right side moves the character to the right.

In the game, thunder boy-kun flies towards the player from the front, and when he gets close, he drops thunder. To avoid getting hit by the thunder, players must move to a position that matches the color of the cloud thunder boy-kun is riding on. If the player is in a position that doesn't match the cloud's color, they get struck by lightning and it's game over.

The objective of the game is to see how far players can sprint without getting hit by thunder. It's a casual game that offers a simple and enjoyable challenge.

Please note that this game was created by the developer as a hobby and for fun. The graphics and overall quality may not be the best, but the developer appreciates the support and encourages players to download and play the game.