Sometimes, a normal computer keyboard will only accept user's inputs up to a certain key simultaneously. I got a logitech keyboard that can accept up to 3-4 key presses at the same time. The computer does not accept any more input if you press more than 4 keys for this keyboard. And it also depends on certain areas of your keyboard as well. Some locations allow more key to be pressed (like the arrow keys), while some locations permit you to press only 1-2 keys. This also differs from keyboard to keyboard as well. Some older keyboards only accept up 1-2 keys.

This isn't problematic with usual office work, but when it comes to gaming. For instance, imagine a platform game, where you have to jump, attack, and control direction at the same time. This implies several key presses and some keyboards cannot accept such simultaneous input. However, I've tried this on several games and the amount of possible keyboard inputs seem to be also different. Therefore, we have two issues:

1. Keyboards have different amount of simultaneous inputs.
2. Some games can accept more keyboard inputs than other games.

At first, I thought this is hardware only problem, but why do some programs behave differently? Why some programs can accept more keyboard inputs than other programs? So how can we write our programs to accept more keyboard inputs?