Outside the Box Project Beta Work - Coin Drop Mechanic

Super Mario Galaxy for the Wii had a cool mechanic where, if played Co-Operatively, the second player can use their controller to assist the first player (who controls Mario) by collecting the in-game currency dotted around the environment. The second player does this by moving their controller cursor over the gems and that registers in-game as collecting the gems and they are added to the total count.

One of our design pillars involved engaging play (it's a game, of course we want it to be engaging), however due to the Tower Defence nature of our gameplay often involves a lot of waiting. Waiting for Enemies to come into range, waiting for Defence to be built, waiting for the Defence to attack etc.

So to reduce disengagement I took inspiration from Super Mario Galaxy and decided to implement Coins erupting from the enemies when struck/killed for the Player to move their mouse over and "Collect" to give the Player more money.
This reduces the likelihood of Players disengaging from the game as to afford to buy Defences and to upgrade them the player must actively collect these coins, and to help incentivise the Player they also sound appealing to collect with a jingle that is played when they are collected and they produce feedback explained later. 

Basically, when the Payer mouses over the coins they destroy themselves and increase the Players total money pot. There is a coroutine here that destroys the coins after 3 seconds have passed regardless so as to preserve Frame Rate and for game balancing, otherwise the Player would be swimming in collectible coins, and consequently, money. 

Later on I added to this script to produce text feedback on screen informing the Player how much to coins give them.

Due to the explosive nature of the coins, and to prevent them just flying off screen and never giving the Player a chance to collect them, I built 4 walls around the game board/camera view circumference. Their sole purpose is to prevent the coins from flying off screen and to do that I simply gave them all Box Colliders that aren't marked as Trigger, so the coins bounce off the walls and back into the game scene.