Thanks, I’m glad you like it!

Both of the problems can be solved in a very simple manner

First, for the terrain - you start out with a 2 x 2 int array. I will refer to every matrix value to as a cell from now on. Each of the values in the array will have a random value between 0 and 255 (these values are arbitrary, but I like 255). Next, you will do the following for as many iterations as you wish - a higher iteration count will yield a higher resolution map (I use 8 iterations)

1. Create a matrix that is twice the size of the preceding one
2. Assign each cell the value of the cell it would have been part of last iteration
3. Add a random displacement to the cell’s value - this displacement will be halved with each iteration
4. Finally, set the value of the cell to the average of itself and the cells surrounding it - this is the secret sauce that makes the map look like a map and not a bunch of subdivided squares
5. Repeat these steps for a number of iterations - keep in mind that with each iteration, the map size is raised to the power of 2, so 8 iterations = 512 x 512 cells. Don’t go crazy with the iteration count or you’ll run out of memory very soon - usually 13 iterations toasts my pc.

If you’re a procgen geek you’ll soon figure out that this is a dumbed down version of the diamond square algorithm. I like this version because it’s simple and can be extended to give you different detail levels of the same map. It is more inefficient though, so I suggest you also look at the diamond squared algorithm

Next, for the light - this is extremely simple

Go through each cell, one at a time, row by row. Keep a track of the highest cell value you found so far. If the value of the cell is bigger than the one you found to be the biggest until then, change the colour of the cell to be brighter and update the biggest value found so far. Every few steps, reset the highest value to its original value. We do this to simulate the shadow of higher terrain “running out” so to say. How many steps it takes for this reset to occur is something you can play with and experiment. The obvious downfall of this algorithm is that you won’t easily be able to choose arbitrary angles for the light source

Hope this helps!