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.

Look at existing compression algorithms in the repository, such as RLE, to understand the structure. The issue describes a 2D RLE for tile maps; start by designing a class that can compress a 2D array of integers by merging consecutive identical rows or blocks. Write tests with sample tile maps to verify compression and reconstruction work correctly.

Written by the indexing model from the issue text.