A neato bandito piece of software Maxis created and published in the US in 1994, and published by Europress in the UK. It was a simple game creation system, but it served as a very good introduction to good game design. If you tried to create a game where you could do anything, you'd soon find it was impossible. If you created a game where you had unlimited lives and you made all the enemies die in one hit, you soon figured out it wasn't really that fun to play.
So you soon realized that you had to create games that were challenging and fun at the same time. It didn't take me too long to create some slick, cool games. Nothing of epic level though. The game was best at creating top-down arcade like shoot 'em ups, although with alot of work it was possible to do some simple side scrolling (Really hard though).
Klik & Play worked by letting the author make "storyboards". On each storyboard you would setup certain events to happen, basically a bunch of if statements. For example:
If Player 1 Shoots Player2:
-Kill player2
-+1 score to player1
-Respawn player2 at x,y
Fairly simple, easy to get the gist of it after a few days. However, this ease of use cause a large sacrifice in power. Every single event had to be recreated for each storyboard, there wasn't anything like functions. RPG's were virtually impossible, since you couldn't bring information from one storyboard to another, like stats (unless you stored it in the player's score).
However, Klik & Play had one big advantage over other game creation softare packages at the time. It could create self executable files, meaning that if you gave someone your game, they didn't have to have Klik & Play to play it.
Corel later licensed a more advanced version of Klik & Play called Click & Create. This made things like interactive stories more viable, and it had built in features for creating things like screensavers, instead of just exe's.
Yes, it was spelled with a 'k' on purpose.
People interested in a good game creation system should check out VERGE ;)