Hamtaro: Rainbow Rescue is a Game Boy Advance video game released in 2003 and 2004. It was published by Nintendo and developed by AlphaDream, creators of Tomato Adventure and Mario & Luigi: Superstar Saga (and various other games in that series). This was the first Hamtaro game developed by AlphaDream, but it is not the last. The game was released in Japan and Europe, though Nintendo of America cancelled it. In Japan, the game was the fourth game in the series and was translated as Hamtaro 4: The Rainbow March.
In the game, you'll go around the world of Hamtaro learning new words to use (called Ham-Chat) in order to solve the game's various puzzles. After you learn a new word, it'll be present in your Ham-Ham Dictionary on the game's main menu. As always, the game contains a variety of minigames that the player can partake in if he spends a certain amount of sunflower seeds.