Here's a simple way to generate random numbers, if you are not getting this functionality from a library already. I've found this sort of function useful for C code on various classic video game consoles:
unsigned int NextRandom = 1337;
unsigned int random() {
NextRandom = ((NextRandom * 14577) % 190) + 25;
return NextRandom;
}
In order to add a bit of chaos to this deterministic function, keep calling the function while waiting for user input, or whenever user input is received. By doing this, you are advancing through the sequence generated by random() a different amount for different users, which can translate to wildly varying outcomes in your game - a.k.a. randomness.
For example, you could implement waiting for the Start button to be pressed to begin the game like such:
// wait for Start to be pressed
while( !START_PRESSED ) {
random();
}
The while loop will likely be executed many times a second, creating very different outcomes for slight differences in how long each player waits until they press Start.
Also, during your main game loop you can check user input as such:
if( KEYPAD_LEFT_PRESSED ) {
random();
//handle left being pressed
//...
} else if( KEYPAD_RIGHT_PRESSED ) {
random();
//handle right being pressed
//...
}Again, some players move around more in your game, so that will affect how far we advance through the pseudo-random sequence.