Algorithm request: Sort-of RLE but on a two-dimensional array of numbers

**Is your algorithm request related to a computational problem? Please describe.**
I don't know the exact term of this algorithm, which I needed for my game, to reduce the a grid-based map data-wise. It is somewhat similar to an RLE-algorithm, but works on a 2D-array instead of a linear buffer/array.

**Describe the solution you'd like**
I already have a solution cooked up, and am reviewing/adjusting it to conform to the guidelines.

Again, I don't know the name but it might be helpful to others, too.

**Describe alternatives you've considered**
Too many, but I forgot the names, unfortunately.

**Additional context**
Context is as stated above. I have a two-dimensional array of numbers (int, short, byte, doesn't matter), where many places are prone to repeat. Imagine a tile-based map where there are a lot of repeating tiles, like grass. I don't want it to consume space each time but instead "merge" (like RLE) so that it can be easily reconstructed again later, saving more space the more repeating context there is.

I am programming a game on the PS1 where I have many maps and I don't want them to fill up RAM. I can easily draw a big rectangle with a repeating tile instead of n tiles of that texture.