Super Mario Time Machine is a game where you have to prevent yourself Mario from convincing Bowser to not kidnap Peach.
Mario is talking to Luigi and says that he doesn't want Bowser to kidnap Peach anymore. Both of them go to Toadworth, where he sends Mario in a time machine to Y2K to convince Bowser to not kidnap Peach. So Mario convinces him, then travels back to the present, which Bowser now rules because since Bowser never kidnapped Peach, Mario thought he was turning into a good guy and never payed any attention to him. Bowser throws a forgetting puffball at Mario, so he forgets what time he travelled to. So he goes to a bunch of different times to find out where he travelled to.
Level 1: Dinosaurs
Mario takes Toadsworth's time machine to the time machine, and Mario looks for himself, and gets lost, so he tries to find his way back.
Travel on foot. Enemies are Paradactyls, G-oombaRexes, and K-TroopaRexes. The boss is a giant G-oomaRex.
Level 2: Ice Age
Mario appears in the Ice Age, and travels on a mammoth, and takes the time machine with him, but falls off and slides away.
Ice skate past the Goombly Mammoths and Koopa-Tooth Tigers. The boss is a giant Goombly Mammoth.
Level 3: California Gold Rush
Mario apppears in the Gold Rush, but falls into a hole where someone is digging for gold and lands in an underground mine.
Find your way through the tunnels. Enemies are Goomba-Diggers and Gold Koopa Troopas. The boss is a huge man holding a pickaxe.
Level 4: Wild West
Mario appears in the Wild West, where a horse carries the time machine away.
Ride a horse to find the time machine. Get gun and lasso mushrooms. Enemies are Goomborses and Koopa Horsa Troopas. The boss is a giant Goomborse.
Level 5: Future
Mario appears in the future, and says he travelled too far. A giant robot picks up the time machine and adds it to a collection of time machines.
Ride the hoverboard past the RoboGoombas and Roboopa Troopas. Find the right time machine. The boss is a time machine guardian.
Level 6: Titanic
Mario appears on the Titanic, where sliding objects come toward him.
Jump over sliding objects. Avoid the Goombsliding Objects and Koopa Passengera Troopas. The boss is a giant Goombsliding Object.
Level 7: Y2K
Mario appears in Y2K, where he discovers that he is really in this time.
Walk past houses. Avoid the Goombhiders and Koophider Troopascareds. The boss is.... you? That's right. He tries to stop you from stopping him. In the end, a time warp opens, because a person cannot meet theirself without a disaster.
Level 8: Warphole
Both yous and Bowser are floating around. More and more things are getting sucked in.
Avoid Goomfloating Objects and Koopa Floating People Troopas. You can switch between Past You, Present You, and Past Bowser. Get to the end. The boss is King Bowser from the present. You need Past Bowser to beat him. Breathe fire at Present King Bowser 5 times to win. Past Bowser, Present King Bowser, Past You, and Present You spin in a circle and create a warphole that redoes everything and you win the game.