In platform games we view the game world from the side and the player runs along platforms, climbs ladders and jumps from platform to platform.  There is gravity, so the player will fall if they don't jump far enough.  Usually there are things to collect and enemies to avoid.

• First of all you need to learn how to set up platform movement for your character. They need to move along platforms, jump and climb ladders.  This tutorial will show you how.
• Next you need to learn how to make your character face the right direction as it moves.  Click here to learn how.
• Next we need to make the background look much better.  Using tilesets solves this problem.  Complete this tutorial to learn how.
• Usually the player needs to collect items.  You can collect things as you did in the maze game. 
• Next we need monsters to add danger and a bit of excitement.

Obviously there are lots more things you can do in a platform game, but you should know enough now to get started with your own game.