Hey there,
I have 7+ years of experience developing games using various game engines, 4+ using Unity 3d.
I have recently completed a similar job on another freelance site ([login to view URL]), where I had to create a 2D level editor for an Endless runner game. The player can select various objects from a menu, and then tap on the screen to place them there. In this way, the player could add any number of Coins & obstacles in the level.
Then, the player could enter a preview mode where he could play the entire game and collect the coins while avoiding the obstacles. This bit of the Preview mode required me to Translate the position of where the coin was placed (screen space coordinates) to the actual position in the game (Unity coordinates)
Let me know if you need more info.
Best,
Ashish