Here's the source code for a Bejeweled clone called Gemgem, written in Python with the Pygame library. You’ll need Python (2 or 3) and Pygame installed to run it. I've tried to keep the source code simple so it's easy to follow and learn programming and Pygame from it. It comes in under 540 lines of code, including whitespace & comments.
To play, click on (or drag over) two adjacent gems to swap their position. You need to swap them so that there are three or more gems of the same type in a row. This causes the gems to disappear and new gems to fall in their place. You get more points for chain reactions or more-than-three matches. The score constantly trickles down, so solve as fast as possible. The game ends when no more moves can be made.
The backspace key will reset the board, the escape key quits.
The graphics were from Osmic on opengameart.org