The game involves the player controlling Felix the Cat as he sets out to defeat the evil mad Professor who has kidnapped Felix's lovely girlfriend, Kitty. The Game Boy version plays virtually the same as the NES version, but features fewer levels.

Felix the Cat has simple game mechanics. The A button is used to jump (press repeatedly to fly or swim), and the B button is used to attack. The type of attack varies depending on the magic level. When Felix falls into the bottomless pit (past the bottom of the level) or when the game clock runs to zero, he loses a life regardless of what his magic level is.

Magic power and common items

At the upper-left corner of the screen, there is an indicator (using hearts) for how much magic power Felix has available. The magic power deplenishes by one every six seconds. It is replenished by milk jars (2 hearts per jar), hearts and F-icons (full recovery). Hearts, from the Felix head emblems, increase the magic power level by one. Depending on the type of exploration involved, there could be anywhere from one to three higher levels than the base. If another heart is collected when at the highest level, an extra life is awarded along with full recovery. The F-icons give full recovery as well as an extra life. Higher magic power levels bestow increased attack power, range, and speed, making it easier to defeat enemies. If Felix runs out of hearts on the indicator, the magic power level is reduced by one, and the heart indicator is reset to 10.

Enemies

Felix the Cat has enemies with simple behaviors, but a large number of them. Some include moles, tree trunks, cannons, birds, fish, and even 8 boss monsters. Bullets and anything fired have 2 routes: a straight line or an arc that goes through the ground. Enemies generally walk horizontally at a constant speed back and forth, bounce up and down for flying enemies, or shoot something—the most complex follow Felix at a slow speed. If Felix takes a hit, his magic power goes down one level. If Felix is at the lowest magic power and gets hit, he loses a life.

The Felix head emblems

The system on how the Felix head emblems work is fairly simple:

• Each one is worth 50 points
• Multiple of 5 but not 10 - 3 milk jars appear
• Multiple of 10 - a heart will appear if not on the highest magic level. If Felix is on the highest magic level, you need to have collected 20 for the heart to appear while in this state which would then give an extra life.
• Collect 100, an extra life is awarded.

Activity states

Felix has many activities:

• On land - This is the most common. There are 4 magic power levels (3 upgrades): base, magician, car, and tank.
• Flight - Flight-based levels involve pressing the A button to remain airborne and fly. There are 3 magic power levels (2 upgrades): umbrella, hot air balloon, and airplane.
• Boat - Boat levels are much like the "on land" levels with the only difference being that you have water below and you are buoyant. The water in these worlds pushes you back toward the start. There are 2 magic power levels (1 upgrade): canoe and dolphin. A boat level precedes a swimming level.
• Swimming - Swimming-based levels are similar to flight-based levels. There are 3 magic power levels (2 upgrades): snorkel, sea turtle, and submarine.

The worlds

There are 9 worlds, generally with 1-2-3 levels within, and all but one with a boss at the end.

• The first world is entirely on land. The boss is worth 10,000 points.
• The second world has flight at the start then 2 on land levels after it. The boss is worth 20,000 points.
• The third world has 2 on land levels to start with a final flight level at the end. The boss is worth 30,000 points.
• The fourth world has on land at first, boating, then swimming followed by the boss which is worth 40,000 points.
• The fifth world first is on land, then flight, then on land again. The boss is worth 50,000 points.
• The sixth world is boating then swimming with no third level. The boss is worth 60,000 points.
• The seventh world is entirely on land. The boss is worth 70,000 points.
• The eighth world has only one level and is flight-based. There is no boss for this world.
• The ninth world is entirely on land. The boss for this world is worth 90,000 points.

Sometimes, between worlds, a telephone conversation resumes, involving the mad Professor and Felix. This normally occurs before the start of worlds 1, 3, 5, and 7.

Magic Bag Worlds

A large Magic Bag is found in many of the worlds. They are entered by standing on top of them and pressing Down. Inside, you find a bunch of Felix head emblems (normally from 10 to 20 of them) and occasionally two large Magic Bags. The one on the right is a shortcut through the level, the one on the left takes you back to where you were originally.