Tuesday, 9 January 2018

Underground Adventure (Duckworth)

Nearer Turn Bear
| | |
100ft Drop Bricked Around Gate Mix Large
| | | | | |
Vast Chasm Heart Deep Wall Entrance E/W Tree Twisty Old
| | | (Rope)
Rock Jumble Chasm Rock Cave Chasm
Sharp Twist Main
| |
West Mine Offshoot Choice Long Drop Twist E/W Dead End
| (Axe) \ | (Parchment) (Dynamite)
Panther Bottom Twisty

I have ported the text adventure "Underground Adventure" by Peter Gerrard found in the book series "Exploring Adventures" by Duckworth publishing house. I worked from a Dragon 32 version. The game is evocative of Colossal Cave Adventure (the original text adventure), in that it involves a descent into an apparently ordinary cave, which quickly turns from a mundane to a magical realm. There is a magical bridge in both and mysterious mists and twisty passages. And a sinister "living gargoyle" (instead of a dwarf) occasionally shows up to throw knives at you.

There are two other Exploring Adventures games. The main purpose of all three programs was to illustrate how to program your own adventure games in BASIC on a variety of 8-bit home computers systems (C64, Atari, Spectrum).

The map above is incomplete. It only illustrates the preliminary rooms. The adventure is quite extensive and took quite a bit of squeezing to get it to fit into the 20K of the MC-10. Most of the classic 8-bit systems had a least 32K to work with. Using my standard techniques described elsewhere in my blog posts, I got it below 20K. I condensed and simplified descriptions and you have to load the direction data from a separate file to avoid reading them into an array variable from DATA statements which then are redundantly left in memory.

In the course of doing the port I changed what I felt were some unclear or inconsistent descriptions and items. The most significant "alteration" was the use of the terms "track" and "cave." For example, there is an instance in which a track must be "oiled" so that it can "slide away" to reveal a blocked entrance. The use of these terms seemed to indicate to me that the "caves" were actually an old abandoned mine and the obstruction was actually an old mining cart, so I "fixed" the use of these terms in various descriptions to fit that theme better.

There were also several errors in the code I got from the Dragon. The axe could be thrown even if it had been dropped somewhere else.  It then would appear in the room you threw it in and could be picked up.  Also there was a place where you could go east but not back west for no apparent reason.

I maintained a save-game feature, but it involves saving and loading two separate array variables. The first file is called "UNDRGAME" the second "UNDROBJS." Couldn't unify them into one array as I have done for other games. Just not enough memory. Little clunky, but workable.

Here's a vid: