Looking for the game's files…
Menus: up and down, Enter, Esc to go back. On a road: left and right steer, up and down change speed, Space jumps, P pauses, Esc leaves. The controls menu (the first screen of the game) takes a game pad or the mouse as well.
Your progress (the roads you have finished) and settings are kept in this browser. Alt+Enter: full screen. Ctrl+F11: 4:3 or square pixels. Ctrl+F12: sharp or whole-number scaling.
Only in full screen can the game have the whole keyboard, desktop shortcuts like Alt+Space included, and only in Chrome, Edge and other Chromium-based browsers (hold Esc to leave full screen).