Click the screen, then type:
FILES LOAD "cube" RUN
Ctrl+C stops a running program. SAVE stores into this browser; use Download to get a file out.
PyxelBasic is an unofficial project that uses Pyxel and is not affiliated with Pyxel or its developer. The name "Pyxel" belongs to its original author. The original author has kindly consented to the use of the name.