Picture this: you're playing a platformer game and you are walking along. You see a red button so you step on it, thinking that it will aid you in completing the level somehow. Suddenly a spike falls down from the sky. You 'die' and have to start the level again, but now you know not to step on the red button.
A lot of games require you to restart the level should you die. However the twist in this game is that restarting is part of the game, instead of a punishment for doing badly.
Each level would have a time limit, and if you didn't complete the level in under the time limit, it would restart, the same as if you 'died'. This means that if there was more than one way to complete the level, you may have to find the faster way in order to advance to the next level.
The real trick to this game would come after a few levels with just these mechanics. Probably in level 3 or 4, you would find a level that changes everything. There are two ways to go, one to a key and one to a door (and the end of the level). No matter how fast you run, if you go get the key, you cannot make it to the door in time. But if you do not get they key, you cannot unlock the door. There is a trapdoor that leads from the area the key is in to the area the door is in, but the lever for the trapdoor is down below, near the door.
If you pull the lever, the trap door only stays open for 3 seconds. And there is no way to jump up through the trapdoor. You may notice, though, that the lever is glowing blue.
Before you have a chance to work out what it means, the timer goes up once again and you restart. You walk down to the lever again and notice that it moves itself, right at the same moment you pulled it last time. You wait for the timer to go up, and then you walk back to the lever again, but this time you pull it as soon as you get there. You restart, climb up the ladder and get the key, walk through the trapdoor that seemingly opens itself, and simply walk through the door.
To cut a long story short, if you interact with a glowing blue object, then that interaction stays the next time you do the level.