
Jet Set Willy for the TI-99/4a, 32k memory expansion required.
You can move Willy using Joystick 1 or keyboard (S,D,Space), Pause using P, and toggle music using M
The programmer has identified this project as a labor of love for which no profit is generated - and for which he receives no payment
In other words, the software is free, the price reflects the manufacturing and selling of the physical cartridge alone.
For more information on the development see the atariage forum: