Platformer Level Analysis

The first level in Donkey Kong Country is a good example of a tutorial for a platformer, here's why:

As soon as the level begins, there is a path in front of the player with bananas leading the way. This lets the player know where they are supposed to go and gives them some space to get adjusted to the controls. This first part also contributes to the story because if the player chose to go into the cave to the left, they would see DK's empty banana hoard AKA the reason for going out and collecting bananas.

 
After that, the first enemy appears on screen. It moves pretty slowly so the player has a chance to see it and figure out what to do. If the player didn't know they could roll into the enemy, they would most likely jump and either avoid it completely or land on top and still kill it.

The next enemy is larger and moves faster, but it is on a higher platform so the player can see it and watch before having to deal with it in the same manner (jumping or attacking). Bananas are on the higher platform as an incentive to go where the enemy is instead of just bypassing it.

After awhile the player comes across a much larger enemy that moves back and forth. Donkey Kong can still kill it by jumping, but if Diddy Kong is in front he will get knocked back if the player jumps on this enemy.

Items you can use in the level are easy to see. The save-barrel breaks automatically when the player passes it so they can start from that point if the player happens to die. Other barrels can be picked up and thrown by pressing the attack button (Y).

There is one other type of enemy in this level- a vulture that does not move but throws nuts(?) that bounce down the platforms. The player can choose to just quickly run past and avoid this or go the more challenging route to get the large shining object.

There is also a box near the last part of the level that can let the player ride a rhino if they jump on it. The rhino controls are very similar to DK's so it is easy to use and the player can get a feel for how these animals can help in future levels by breaking walls, killing enemies, etc.

Lastly, the player has an incentive to explore the highest, potentially more dangerous platforms because there are usually hidden items such as extra lives, large bunches of bananas, or signs such as the one above that lead to other useful things.