This project has a ton of existing resources to help you, and a simple compiler can be completed in a few days. Don't let the jargon scare you. Plus the possibilities are endless to what you can add! Once you have the basic compiler working, you can add a standard library (in PeayBASIC I added simple 2D graphics functionality), optimization passes, and improve the error messages. Finally, you should write some example programs in your own language to show off to the world!