Algodoo

I have an idea so when the red circle disappears, the blue does to.

In the onDie section of the script menu for the red circle put:
(e)=>{
scene.my.RedHitBlue = 1
}

In the postStep section of the script menu for the blue circle put:
(e)=>{
scene.my.RedHitBlue == 1 ? {
scene.removeEntity(e.this)
} : {}
}

win

I WoN

Won!

easy win!