If you like to play games on your CD-i player you will probably have a CD-i gamepad or the original CD-i touchpad. Philips did not supply a game controller with CD-i as a standard feature, but delivered a thumbstick with it. That was a clever and innovative pointing device for any kind of reference or movie title, but for gaming it was pretty clumsy. The Philips CD-i Touchpad (22ER9017) and CD-i Gamepad (22ER9021) were official Philips products, dedicated to gaming on CD-i. If you look closely to the design, you'll notice two things. They both have a speed switch, which changes the speed of the cursor on screen. And they both offer three action buttons, but the third button is actually a combined press of button 1 and 2 at the same time. Why?
1. The speed switch
The speed setting on this gamepad /controller. it can go to N, I and II. What games may benefit from this? The speed setting its usefull with games like the Pong style games on CD-i: on family Games 1 there is Wizard and on Family Games 2 the same game with different style. For Chaos Control the speed selection can be quite handy. The same goes for for the shooting sequences of Burn Cycle. The higher the setting, the fast the screen or character moves over the screen, which means you can reach the different edges faster.
2. Button 3
Just like the thumbsticks, mouse and trackballs, CD-i pointing devices offers two action buttons as a standard. In certain games this appeared to be limited and Philips wanted to offer three sction buttons. But of course they couldn't just change the protocol, so they used a trick to offer a third action button: A combined press of button 1+2 would become button 3. This means on classic pointing devices like the thumbstick and mouse you could mimic button 3 by pressing button 1 and 2 at the same time.
Some games use buttons 1&2 as a button 3. In Burn:Cycle, it's used to skip FMV sequences. In some other games, it just pauses the game. In the CD-i Zelda titles, it does nothing. Flashback use all 3 buttons. And there are probably more!
[Thanks, Jaap Jansen, Erik Jacob, Arethius RGC, Adrian Zanolli]