[Drakim]

Zelda 1 has TONS of built-in compression, and it's own decompression routines.

[jsheard]

I should have worded that better, I meant no UPX-style end-to-end compression like the OPs project used. NES games had to be much more judicious than that since there wasn't nearly enough RAM to decompress everything at once.

[throwawee]

Yep. Each screen is just a list of prebuilt columns reused over and over. Then they used a form of crude RLE on the lists.