Illinois Mono is a monospaced typeface based on Lexend, a font known for readability.
(Here is a video explaining how Lexend increases reading speed)
(Regular version above, Medium version below)
Notable changes from Lexend include:
- Double-storey 'a' to distinguish from the 'o'
- '1' without bottom serif, to distinguish it from the lowercase L used by some fonts
Most other changes are to fit monospace style.