Return to Sorcerer's Island for the 16K ZX81

This is a modernized version of the classic ZX81 text adventure "Sorcerer's Island" that came on the A side of the Fantasy Games cassette by Psion. As a marooned adventurer, your task is to find a way to escape the island! On your quest, you inevitably find enemies you have to deal with, while preserving your strength - should your life points ("LP") ever drop to zero, it's game over! Remember that you don't have to fight every time - use your wits to stay alive and explore the island!

The original had an awkward text command system that has been reengineered into a hotkey approach, where every available action is performed by hitting the indicated (inverted) key. Movement is performed through keys 1-8 according to the compass rose whenever possible. 

The game is written from scratch in C, with a few assembly routines (most notably scrolling of text) for good measure. From the original game, I reverse-engineered the obfuscated map (which intriguingly enough contains not only the landscape, but also landmarks and special places) and the algorithms for fighting, fleeing, bribing your way through the map, as well as all original descriptions and monsters (almost- see below).

These are the changes in this updated version, which I hereby call Return to Sorcerer's Island:

• Much faster gameplay as the entire game is now written in C and a bit of Z80 assembler instead of BASIC

• Map is always visible when playing

• One of the strategies in the original game was figuring out how much of your life points to spend when fighting, or gold to buy your way out of a fight. As this quickly became "double his amount plus ten" I have eliminated this part, and the game simply makes a reasonable estimate for you, using the randomness of the original formulas of course.

• One-key gameplay where your available actions are always visible, using the inverted letter as the command key (movement as depicted by the compass using keys 1-8)

• A high score has been added, to encourage repeat play (even if you happen to die - which happens a lot)

Hopefully, all the bugs have been ironed out, but leave a comment if you find anything weird, and I'll try to update it. 

I was surprised at how fast I ran out of memory. I actually had to shoehorn the code in 16k! (Which is the required minimum). Originally, I had planned to add more functionality, a bit of graphics, and so on, but most of that had to go, including any dreams of a title screen or even instructions!