Instructions
Start the game and then click "Play" and "New Game."
Click "Cell Stage" when asked which stage you want to start on.
Click "Carnivore" when asked to choose your diet, then choose any difficulty setting.
Move your organism around with your mouse and swim over the bits of red meat to pick them up. Click the blue "Call Mate" button at the lower middle of the screen to mate with another organism and produce an egg. This will open the cell creation screen where you can add or remove parts of your organism.
Click on the mouth attached to the creature and drag it to the left of the screen to swap the carnivore mouth for an herbivore one. Click the "Filter Mouth" on the left and drag it onto the creature.
Click the "Save &Exit" button at the lower right of the screen to return to the tide pool. Swim over and eat the green bits in the water now, instead of the meat.
Alternate between the "Jaw" and "Filter" mouth to get equal amounts of meat and plant for your organism. Pick up any silver icons you see. Creatures release these when they are killed. The silver icons are "cell parts" and give you more options when customizing your creature. There are six cell parts in the first phase of the game. The most sought after is the "proboscis," which instantly turns your organism into a omnivore, but this can be hard to get, as the creature that has it moves very fast. Your best bet is to wait until it falls prey to one of the larger, faster creatures; then you can swim over and pick up the cell part icon.
Press the "Call Mate" button when you get the message that your creature is ready to evolve and go on to land. Attach the "Proboscis" mouth if you managed to get it, otherwise attach both the "Jaw" and "Filter" mouth to your organism. The creature type indicated at the top right of the cell creation screen will indicate that your organism is now an "omnivore."
Save and exit the cell creation screen and click the blue "Advance To Creature" button at the bottom right of the screen. Select a pair of legs for your organism and afterwards it will enter the creature phase as an omnivore.