In order to complete the Chain Gang level on Miniclip ClickPLAY, you need to click on each chain and drag them towards the top of the screen to get to the ends. On the third chain you pull, the "Play" button will appear, and you've completed the level.
Miniclip ClickPLAY sequels
If you'd like the same experience that Miniclip ClickPLAY provided, your best bet is to try out ClickPLAY 2 and ClickPLAY 3, which offer the same types of challenges at the first game.
If you'd like to try your hand at something more challenging, however, there is now the option to play the ClickPLAY Time and ClickPLAY Quickfire series. These games follow the same pattern of solving puzzles to find the "Play" button, but you're also timed. The speed element makes things even more tricky, but it's loads of fun!
If you get stuck, you can always check out videos like this one. They're pretty fun to watch even if you don't need help!