Mushroom Grassland is the first world in New Super Mario Bros. X-treme. It is the easiest world in the game. Like every other first world, it is grass themed. Lemmy Koopa is the boss of this world
1-1: Grassy Way
The first level in the game. It will have Goombas and Koopas.
1-2: Crystal Caves
The first underground level in the game. Koopa Troopas and Goomba Towers appear in this level. There's a secret exit to 1-a
1-A: Cheep Cheep Bridge
The secret level of World 1. It will take place on a wooden bridge with Cheep Cheeps. Completing this level will take you to World 4
1-3: Yoshi Forest
A forest/grass level that will introduce Yoshis and Hammer Bros.
1-Fortress: Goomboss' Cog Fortress
The tower of World 1. Cogs and Dry Bones are in this level. The boss is Goomboss
1-4: Mushroom Skies
A sky level with mushrooms and Paratroopas
1-5: Chargin' Chuck's Cove
A grass level with types of Chargin' Chucks and Piranha Plants. Lemmy's airship will be circling his castle at the end of the level.
1-Castle: Lemmy's Fencing Castle
The castle of World 1. There's lava pits, pillars, and grates. The boss is Lemmy
Goomboss will act like Mega Goomba like NSMB, but he's smaller and there's moving platforms. Hit him 3 times.
The first Koopaling. Lemmy will launch circus balls and bounce on his ball. After 2 hits, he'll throw Koopa Shells.