Four Gem is a minigame on Animal Jam which is based on the game "Connect Four". It can be played by one or two players. You can send out an invitation for this game (press the Actions tab, then click the controller icon, then click the icon that says "Four Gem"). You could also click a player's tag to access his/her card, click the controller icon, and click "Four Gem."
The object of Four Gem is to match four of the Gems that are your color. Click the square where you want to drop your marble. Possible matches can be made horizontally, vertically, or diagonally. The winner receives 20 Gems. The loser receives 5 Gems and an opportunity for a rematch. However, the winner has the choice to reject a rematch.
The achievements below apply to all buddy games in general: