A band of greedy Neanderthals has taken all the Cavewomen. It is up to Joe and Mac to rescue them by facing through many angry animals (such as Ichthyosaurs, a T-rex, or an Elasmosaurus).
The gameplay of very similar to Super Mario Bros., but Joe (the green haired Caveman) and Mac (the blue haired Caveman) are given unlimited weapons to throw. If Joe or Mac dies, one of them will lose their weapon. Every stage (excluding the Game Boy version) ends with a boss fight.
Joe or Mac have long health bars that steadily drain.
Food items are exceedingly common, and must be frequently collected to survive.
There are multiple paths to choose at the end of certain levels.
There are three endings, chosen the same way as alternate paths are, but at the end of the final level.
Joe and Mac have a full suite of weapons, including axes, bones, boomerangs, fireballs, electric sparks, stone wheels, dinosaur teeth, and ghostly doppelgangers.
Joe and Mac have a charge attack that allows them to throw larger and more powerful projectiles.
Joe and Mac do not have clubs, only projectiles.
There is a level where Joe and Mac ride the heads of plesiosaur-like creatures down a river.
There is a power-up that causes Joe and Mac to stumble around breathing fire, which damages enemies.
Baby T-rexes act like bosses. The Baby Rexes also got increased during boss fights with similar to an Adult T-Rex.
The feature where enemies and bosses flinch after taking sufficient damage is removed, making boss battles more difficult.
There are two serpent bosses, compared to one in the arcade version.
There is a red Pterodactyl as a boss.
Only the bone, boomerang, fire, and wheel are available as weapons.
The Heart Devil replaces the Mutated Caveman. He has two phases unlike the Mutated Caveman.
The Mutated Caveman doesn't appear.
The Volcano Grasslands is the first level. Joe and Mac fight through enemies, such as Neanderthals, Pteranodons, and a giant T-Rex.
The Tyrant Forest is the second level. Enemies here include Mandrakes and Electric Catfish. The boss here is a Giant Mandrake.
The Stinger Treetops is the third level. Beehives are in the area, so Joe and Mac must be extremely careful. The boss here is a Giant Pteranodon.
The Log Ride is the fourth level. There are many Water Streams, which slow down Joe and Mac. The bosses here is a pod of angry Ichthyosaurs.
The Waterfall is the fifth level. Joe and Mac are carried by Pteranodons. They must avoid the rocks that fall. The boss here is a Brachiosaurus.
The Plesiosaur Ride is the sixth level. Joe and Mac are riding on Plesiosaurs. They encounter dangerous enemies such as Piranhas, Pteranodons, and Archaeopteryxes in here. The boss here is a Brachiosaurus.
The Volcano Outlands is the seventh level. Joe and Mac are facing dangers now, because of many types such as a Gray Serpent or an Ankylosaurus.
The Rocky Cliffs is the eighth level. There are tons of rocks here. The boss here is a Giant Pteranodon.
The Jewel Cave is the ninth level. The boss here is an angry Woolly Mammoth.
The Dinosaur Graveyard is the tenth level. The level here is much harder, as there are Archaeopteryxes. The boss here is a giant Skeleton Dinosaur.
The Dark Outlands is the final location. Enemies here include Gallimimuses, Archaeopteryx among others. The boss here is a giant Red Serpent.
The Serpent's Heart is the inside and the Boss Location. The inhabitants here are Pteranodons, a Mutated Caveman, and the Heart Devil.
Weapons - There are eight types: Boomerang, Axe, Thunder, Dinosaur Teeth, Stone Wheel, Bone, Fire, and Doppelganger. The Boomerang will return after a toss. The Bone fires rapidly in a downwards arc. The Axe is the basic weapon, and acts like a slower bone. The Fire and Electricity deal high damage in a downwards arc, but certain enemies are immune to them. The Teeth fire rapidly in a straight line, but have limited range. The Stone Wheel deals high damage, crawls along the ground, and is generally considered a candidate for best weapon in the game, though it is a poor choice for attacking flying enemies. The Doppelganger weapon cause Joe and Mac to fire spectral clones of themselves, which tackle and punch enemies, dealing high damage; this is considered the other candidate for best weapon in the game.
Food - Food will replenish Joe and Mac's health.
Eggs - An Egg can contain different things, and must be broken open. They will contain a Food, a Weapon, or a Pteranodon enemy.
Neanderthals - Neanderthals are common enemies in the game. They attempt to throw rocks, ride planes, drop bombs, hide in bushes, or carry eggs in the game. They can also attack with their clubs.
Pteranodons - Pteranodons will try to swoop at Joe and Mac.
Rocks - Rolling Rocks are the annoying enemies in the game.
Baby T-Rexes - These will try to eat Joe and Mac.
Mandrake - A Mandrake can be annoying in the player's path.
Electric Catfish- A fish with an electric aura that leaps straight-up out of water. They are very weak, but immune to electric attacks.
Bees - Bees are released from beehives.
Beehives - Beehives must be cleared in order to proceed.
Archaeopteryxes - Archaeopteryxes will shoot feathers to slow down Joe and Mac.
Piranhas - A Piranha will jump out of the water in arcs to attack Joe and Mac. They are also spawned from the Brachiosaurus.
Gallimimuses - A Gallimimus is much more aggressive than a Baby T-rex.
Centipedes - A Centipede is spawned during the battle of the Mutated Caveman.
Giant T-Rex - The Giant T-Rex is very simple. Its throat is its weakness.
Giant Mandrake - The Giant Mandrake attacks by using its vines or spewing Mandrakes. The best weapon to use is the Stone Money.
Giant Pteranodon - The Giant Pteranodon attacks by swooping or throwing Pteranodon Eggs.
Ichthyosaurs - A swarm of Ichthyosaurs is attacking. The best weapon to use is Thunder.
Brachiosaurus - The Brachiosaurus attacks by charging, spitting water, or spewing Piranhas.
Serpent - A Serpent will spew enemies from its mouth. Its throat is its weakness.
Ankylosaurus - The Ankylosaurus will roll in the arena and throw spike balls. It takes damage when it's not rolling.
Woolly Mammoth - The Mammoth attacks by lobbing Rocks or causing falling rocks. Its face is its weakness.
Skeletal Dinosaur - The Skeletal Dinosaur attacks by spawning miniature versions. Its fragments collapses into pieces for hitting it. Joe and Mac must avoid the pieces and then hit its head.
Mutated Caveman - The Mutated Caveman attacks by spewing Centipedes. The Heart deals more damage, because he is much tougher.
Heart Devil - The Heart Devil has two phases. The first phase is when he spits out fireballs and then trying to pierce Joe and Mac. He also clones Mac or Joe. The second phase is much harder. He throws fire rings to make it a shape of a triangle. He also throws fireballs or create fire columns. He can morph or throw fire rings. He's only vulnerable when he's not flashing.
Serpent's Heart - The Serpent's Heart spews many sorts of creatures. Joe and Mac must defeat all the creatures.