Commodore 64 Full Game in Assembly Language - Cryptmorrow C64: Build a Complete C64 Dungeon Explorer in Assembly for the Commodore 64 (code&books)

Build a complete Commodore 64 game in assembly, one playable step at a time.

Under the hill of Morrow lies a crypt of sixteen rooms. Torches burn in halls green with moss, skeletons still guard the corridors, bats wait in the dark, and three seals open the portal of the Moss Gate. Cryptmorrow is an original dungeon explorer for the Commodore 64, and this book shows you how to build it yourself, from the first byte on the screen to the finished game with its title, its music and its endings.

The complete game is yours. A free companion repository on GitHub holds the full source code of Cryptmorrow under the MIT license: the finished game, all eight steps of the book, 22 ready-made experiments, the automated tests and the tools. The game is also there ready to play, as a PRG file and as a 1541 disk image. The address is printed in the book.

What you will build

• A multicolour bitmap dungeon drawn from a catalogue of 2×2 metatiles, with flickering torches
• An explorer who walks, stops at walls and swings a sword
• Sixteen rooms in four zones, each with its own colours, and a HUD with energy, keys, seals and a six-digit score
• Keys, locked doors, treasures, potions and three seals that open the way out
• Skeletons that patrol and bats that chase, with blows, damage and GAME OVER
• An original SID soundtrack and eight sound effects, with a MUSIC, SOUND FX or SILENT menu
• A title screen in big stone letters, victory and defeat screens, and a packed program that unpacks itself when it starts

How this book teaches

• No assembly experience needed. Every instruction is explained the first time it is used.
• Eight playable steps. Each step is a complete program you assemble and run, and its size and SHA-256 fingerprint tell you that you built exactly the program in the book.
• Real code, real screens. Every listing is taken line for line from the source code you download; every picture of the game is a screenshot from the VICE emulator, nothing drawn or retouched.
• Make it yours. Guided experiments change speeds, colours, damage, music and names, with safe values and the way back.
• Where it breaks. Classic mistakes made on purpose and explained: the forgotten bit, the missing jump, the high byte left behind.
• Measured, not guessed. Cycles, memory and loading times are measured in the emulator, and automated tests compare every frame of play with a model of the game.
• Questions with answers at the end of the chapters, a glossary of 86 terms and an index.

Inside the book

Your workshop · Memory and the VIC-II · The tile engine · Text, torches and the frame · The explorer · The dungeon and the HUD · Objects, doors and the portal · The enemies · The blade and the damage · The SID and the music · Effects and sound modes · States, title and end screens · Packing, loading, measuring · Reading and checking the game · Glossary and index

What you need

A Windows PC and three free programs: the 64tass assembler, the VICE emulator and Python. On Linux the same commands can be typed by hand. The game is written for the PAL Commodore 64 and was tested in VICE.

Cryptmorrow is the second volume of the C64 Game Manual Series, where every book is independent and brings a new original game to life. Start the emulator, light the first torch and step under the Moss Gate.