The Paradroid transfer game is a sub-game that was used to determine if the player is worthy to take over a new robot, having already managed to get close enough to it.
(Thanks to whomever posted the above and below pictures on the interweb).
The game consists of two sides of power lines to the central column. One side is controlled by the player, the other by the robot you're attempting to take over. The objective is to fire your colour from the edge, through the wires to the central column and gain the majority of the column before the countdown completes. You fire colour down the wires with a limited number of power blocks that you guide 1 by 1 to the wire you want to fire down, and then press the button. The number of power blocks each side gets is dependent on the type of robot you both are. The higher level robots get more shots. If the difference is too great you will likely lose, so it is best not to attempt to transfer to a very high level robot from a low one.
The wire arrangements on each side are set up randomly. The player's advantage is that you get to decide which side you want to play from. Since there are an even number of coloured blocks in the central column: a draw can occur, and a replay ensues. In an early incarnation of the transfer game I resolved the draw by randomly deciding a winner. My test team were up in arms about that: it took away their self-determination and offered the toss of an electronic coin, they hated it. I therefore allowed a replay, and they were happy again. I agreed with them, it was much better, even if you get 3 or 4 draws before resolution.
History
The design of Paradroid was, unusually for me, well decided early on. I had a piece of blue note-paper and had come up with the design thereon as I was walking home one evening. The transfer game though, was not part of the original design. The game was coming together on the C64 and it just seemed right to make the player earn the reward of the new robot. I didn't have a lot of spare space so I wanted to be able to make the game from a few 8x8 character graphics. I didn't stoop to using the existing game characters, but the whole game looks to use only about 25 characters.
Zzap!64 magazine was publishing a monthly diary of the game. From that I read that the transfer game took me a week to design, code and debug. The tricky bit, as I remember, was to set up a valid layout of power lines. You get splitters, joiners, dead-ends and power generators. The splitters and joiners affect 3 consecutive rows of wires, and some combinations are impossible. I spent a fair amount of time setting up the rules and testing, only to see a loose wire.
Layouts
I start the layouts by putting the characters on the screen to connect the outside to the central column by straight wires. I then work from the outer sides and decide between a splitter, joiner, dead-end, power generator, polarity/colour changer or to leave the wire alone, and drop in the characters over the existing wires, modifying the layout. I believe one restriction was that you couldn't have an outer colour changer, as that might mess up the inputs to a joiner.
Working from the top, if you place a splitter or joiner it modifies the next 3 wires, so you can't start one of those if you've already started one on the previous 1 or 2 lines, nor can you start if you're already on the last 2. I can't remember if there were particular weightings on the different elements, likely there were. It was not influenced by the robots involved in the battle, only the number of shots available are set by the robot designations.
After doing the outside elements, it then assigns the inner elements. There are slightly more rules on the inside elements because some wires may not get to the second element. Everything was driven from the on-screen characters to know what's allowed.
I added the robot sprites at the top to show which side is the player, so it didn't take any new graphics. The player gets a few seconds to decide which side to play. That's not usually too difficult a decision as it's either to see or it doesn't really matter.
Play
For as many shots as the player has, you just move the power generators up and down until you find the wire you want to fire across, and press the button. The C64 version applied no intelligence to the robot player, it just picked a wire at random, went there and tried to fire. It may therefore try to fire at a dead-end. It would then select a new random wire and carry on. Thus, even if you give the robot player the best side, it may not take advantage of it.
Power is transmitted across the wires by using one array for each side of 3 sets of 12 one-byte unsigned variables. The variables represent the 3 points along each wire from the outside, to between the two elements, to the inside. Zero means no power.
The wire process just moves down the wires, and considers one side each alternate game frame. When a power generator is fired, it sets the variable for the outside part to the time it wants it to last. Each game frame then, where there is a valid wire, any non-zero value on the outside is decremented and the middle section, if not 255, is incremented. Any 255 value represents an active generator and is not decremented, but a 1 is passed along the wire, again unless there is another 255 value representing a second generator Splitters send a +1 to the above and below wire variables, and a joiner requires that there be a non-zero number at both upper and lower wires to pass the +1 to the output side. A power generator that has been started gets a 255 value that indicates it is permanently on, this value is never decremented. Any non-zero value then also modifies the wires to be coloured and animated characters on screen rather than inactive black. These could be the other side's colour if there was a colour changer. Wires revert to black when their input side counter reaches zero The colour of the wire coming in is then also applied to the central column, if it's not black. Since the process alternates sides on each frame, any central column being fed from both sides will flash between the two colours.
The Paradroid '90 Transfer Game.
When I got to the 16-bit machines I wanted to beef up the transfer game a bit. Firstly, it was all done with graphics rather than characters. I would use the word "sprites", but that implies hardware sprites, and the Atari ST didn't have any, and I didn't use the Amiga hardware sprites for the transfer game either. Secondly, I wanted the robot player to be a bit smarter, i.e. not only would it not fire down a dead-end, it would absolutely trigger any power generators to its advantage, and also not fire at any colour-changers. This meant that after the layout was generated in the same way as the C64 version, and just prior to getting a new shot, it would evaluate the layout it had been given and internally decide the best wire to fire along. It will favour splitters, then generators, then straight wires, then joiners and ignore colour changers. You can see it wait as well if it has already fired along every wire it needs to. I also allowed the robot player to use the wraparound feature to move up from the top to appear at the bottom to get to the lower wires more quickly. The player can do that already, so why not the robots?
I added a couple of extra wire lines to fill the new bigger screen area. It took me two weeks to do most of the graphics and code the game this time. I had some help with some of the graphics. Despite having the design nailed down and the C64 code to refer to, I had to devise a way of controlling the game that didn't refer to the 8x8 characters that were the heart of the C64 version. The better "intelligence" of the robot player also made for a tougher game. I had to slow down its fire rate slightly as it tended to spend all of its shots too quickly. One player tactic for both versions is to save your shots until the last couple of seconds.
The later ships were bigger on the 16-bit version of Paradroid than the C64. I did replicate the C64 original ship layout for one early ship, as a nod to the original. The bigger ships made for a longer game, and originally as a debug feature I rigged up a bypass of the transfer game. Someone suggested that be left in as an option, so you can select to turn off the transfer game on the options page before you start. You then automatically win the transfer to the new robot. That makes the game shorter and easier, though you still have to sneak up on the robots and avoid incoming fire. There's another consequence too: with the transfer game off you definitely won't be going to the secret pirate ship at the end. Aren't I mean? Has anyone ever seen, let alone defeated, the final marauders' pirate ship?
