This tutorial will guide you in writing a simple Tetris game in XC=BASIC. The game is relatively easy to implement and I think it is going to be a good start to get you started.

• Step 1: Setting up the development environment
• Step 2: Planning the game
  • Step 2.1: Designing the screen
  • Step 2.2: Designing the shapes
  • Step 2.3: Designing the playfield
  • Step 2.4: Planning the program flow
• Step 3: Coding
  • Step 3.1: Defining data and variables
  • Step 3.2: Coding the routines
    • Step 3.2.1: Finding a shape
    • Step 3.2.2: Testing if piece overlaps
    • Step 3.2.3: Drawing a piece
    • Step 3.2.4: Locking a piece
    • Step 3.2.5: Clearing a row
  • Step 3.3: Coding the loops
    • Step 3.3.1: The update loop
    • Step 3.3.2: Checking how far we've got
    • Step 3.3.3: The game loop
    • Step 3.3.4: The program loop

I will try to explain most of the things as detailed as I can but there are some assumptions I'm making:

• I assume you know the Commodore BASIC (CBM BASIC or BASIC V2) programming language. I'll only explain commands that are different in XC=BASIC or don't exist in CBM BASIC.
• You're familiar with the Screen RAM and Color RAM.
• You understand bitwise operations OR, AND, XOR.
• You're okay with binary and hexadecimal numbers.

If you need to refresh your memory, I suggest you to refer to the Commodore 64 Programmer's Reference Guide.

My name is Csaba (IPA: [ˈt͡ʃɒbɒ]) Fekete and I'm the author of XC=BASIC. If you have any questions or suggestions feel free to email me to feketecsaba (at) gmail (dot) com or mention @xc_basic in your tweet. If you like what I do, consider supporting me on Ko-fi! Thanks for reading!