In Cobi Treasure Deluxe you have to help Sally the seahorse collect and match ocean treasures. The game has three game modes: Classic, Ship Shape and Sally’s Shape.
Each of them revolves around cleaning the playfield from gems of different shapes and colors falling from the top of the screen. To do so, you have to match three or more of them. The more gems you match at the same time, the more points you get. The player can control the game with mouse or arrow keys. Moving mouse horizontally or pressing left and right keys position the falling gems, clicking left mouse button or pressing up rotates them and right mouse button or down critical speeds up the rate of fall. There are several types of unique gems that affect the playfield one way or another.
For example, Oily Glooper spreads to any adjacent gems turning them into Oily Gems that can only be cleared by Danger Gems. The Classic game mode consists of 75 levels in which you have to score a certain amount of points. Ship Shape is an endless mode where the water gradually fills the screen.
Matching gems makes waterline go down. In Sally’s Shape, you have to clear Puzzle Shapes before the timer runs out. The game has a trophy system which awards the player for completing different challenges and registers the player’s high scores.