I've made the multi-platform (PC/Linux/Mac) multi-platform (ZX Spectrum, C64, Plus4, Amstrad CPC, MSX, Sinclair QL, Atari ST) paint program called Multipaint. The first release was 2016, and the newest version is Multipaint 2020.
Go on, pick your (preferably two-button, wheeled) mouse and start pixeling!
For more information, download and an image gallery, check the home at:
Multipaint 2020 at Commodore Scene Database: