Digger Deeper Into My Water Bug II Game for the ZX81

For years, Water Bug II has been an interesting game for me. I was so excited when completing the first version, that I wanted to build another one with ten more boards. The funny thing is, the two games look a lot alike. In fact, if you weren’t paying attention, I wouldn’t be surprised if you thought you were playing the same game. Let’s dig deeper on both the similarities and the differences.

# The introduction.

The title screen should look pretty similar. I was pretty proud of the first one in the original. But I added a little more this time with a rotating credit at the bottom. This is the final version. I first created a test one using an “se-graphics” logo. I was having fun thinking about running my own company back then. It wasn’t to be, but the idea lives in some of my different programs and games from that era. The final version in WBII swapped that out for a simple “(C) 1984” instead.

Water Bug II, Introduction, ZX81 Screenshot, 1984 by Steven Reid.

Now, the actual code to make the rotating logo work is pretty simple. I put the text in an array and then then print the first 128 characters (what you see) to the screen. Then, I rotate the top line to the bottom of the array in a loop. The code works pretty well and has a nice look too.

# Board 1: A familiar start.

Now, Board 1 should look really familiar. It is pretty much the same board as the first Water Bug. In a way, I was trying to tie the two games together with the same intro. The program, however, is very different. I reorganized things quite a bit and cleaned up some of the code as well. Instead of a new game, Water Bug II is more of a rewrite with new boards.

Water Bug II, Board 1, ZX81 Screenshot, 1984 by Steven Reid.

Completing the board, you’ll get a random score as before. Some things never change. In fact, I didn’t fix my math problem either. Oh well. The transition is also the same, nothing new there either. At this point, the two games play the same and look the same. Although it adds some continuity to the first, I really should have changed the first board up a bit.

Water Bug II, Board 1 Complete, ZX81 Screenshot, 1984 by Steven Reid.

# Board 2: Cheating again.

Going into Board 2, things continue to look the same. However, this time the secret path is a bit more complex. Now you have to go along the bottom first and then along the right edge to display the treasure. A bad design, in my modern opinion, but again I was the only one who was ever playing it. As noted last time, I really should find a better game mechanic for this board or, perhaps, leave it out altogether. Let’s move on.

Water Bug II, Board 2, ZX81 Screenshot, 1984 by Steven Reid.

# Board 3: Some real gameplay.

Board 3 is really the first departure that Water Bug II takes. It skips the scrolling board from Water Bug, instead presenting you with the moving treasure from Board 4. However, instead of pillars you now have random inverted asterisks and minus signs. Having used those as switches perviously, the minus signs will kill you. But, if the treasure hits one, it randomly teleports somewhere else. Not very nice. Overall still an easy board. I do like the mechanics and it starts to show that Water Bug II isn’t just a repeat of the previous game.

Water Bug II, Board 3, ZX81 Screenshot, 1984 by Steven Reid.

If I were to fix anything in this board, I’d redo the switches and use a different graphic. In that way, it would be more obvious that they aren’t something the player should touch. Continuity is key in a game like this. Now, to make the board even more fun it would be cool if the user could touch and get teleported as well. To be honest, I doubt anyone would use it as it wouldn’t really help as the board is current designed.

# Board 4: Amping up the play.

Now Board 4 should look familiar. It is a variation of Board 8 and Board 10 from the first game. Here you have two scrolling barriers with a switch. There are also three vertical barriers you have to navigate through. You have to navigate through the scrolling barriers first and go tag the switch. It will then reveal another switch. Navigate across and hit it to reveal a the treasure and an enemy asterisk.

Water Bug II, Board 4, ZX81 Screenshot, 1984 by Steven Reid.

Now outside of some strategy to get the enemy away from you, it is really just a game of getting through and grabbing the gold. My strategy was to lure him up towards the top first and then head through. Note you can’t bait the enemy into another tower, I added a check to prevent that. Just a mad dash to get down to the treasure.

# Board 5: Let’s have some fun!

Now Board 5 is another variation of my favorite board from the first game of the same number. This time, however, the rotating seaweed is in the center of the screen. The seaweed now has a barrier as well, making you move around a bit to get to the switch. This time, the treasure gets placed into the rotating seaweed, making it a bit of a challenge to grab. I’m so mean.

Water Bug II, Board 5, ZX81 Screenshot, 1984 by Steven Reid.

At this point, you are halfway through Water Bug II. Now, as before, any deaths drop you back to the start and it only gets harder from this point on. Water But II is not a forgiving game, even more so than the first.

# Board 6: A shift in difficulty.

With Board 6, I really go off the deep end. This time you have a quadrant of boards and a switch. Nothing super exciting. Except for the 4 rotating barriers in the middle of the board. Yeah, that is tough. In fact, it is pretty hard to get through at all. It took me a good number of tries to get to the first switch.

Water Bug II, Board 6, ZX81 Screenshot, 1984 by Steven Reid.

There are a couple problems with this board. For one, too many blocks and not enough room to move. The patterns are hard to follow. The second problem is the routine that checks what you hit is off. You’ll often hit something you didn’t actually hit. It is very confusing and frustrating.

I have mixed feelings on this level. On one hand, I really love the look and challenge. On the other it feels unfair and glitchy. Not a great place to be playing a game. I can’t even think about playing this on a real ZX81 with the crappy membrane keyboard. Great to see innovation, but this board needs some work.

# Board 7: Back to fun gameplay.

Board 7, fortunately, is not as mean. It is a redo of Board 4 on the first Water bug with pillars and a moving target. This time, though, you have to do it twice. The first tag is to touch a switch. The second is then to tag the treasure. Both move randomly and are quite hard to tag. Careful not to touch a wall trying to get to them. At least you get a breather before the next board.

Water Bug II, Board 7, ZX81 Screenshot, 1984 by Steven Reid.

# Board 8: Impossible gameplay.

Board 8 is pretty much a replay of Board 6, but with a different design. This time, you have to get past two small rotating barriers. There is a way through as I planned it on graph paper. But it pretty much sucks getting through once, much less 4 times. You’ll have get to the switch, then retrace your steps back.

Water Bug II, Board 8, ZX81 Screenshot, 1984 by Steven Reid.

Again, great innovation, but it sucks as a level. Water Bug II is like a very hard, balls to the wall version of Water Bug. Yeah, it's tough. I thought I was being clever when I designed this. Let me say, clever doesn’t equal fun.

# Board 9: Potential to be unfair.

Board 9 is a pain as well. It looks simple, with a blank screen, a switch and an enemy. This time, you touch a switch and the enemy turns into a white dollar sign. Sound familiar? It like the game of tag from the Board 6 in Water Bug. Yeah, I didn’t like it then, I still don’t like it.

Water Bug II, Board 9, ZX81 Screenshot, 1984 by Steven Reid.

The visual is at least more obvious this time, but no less a pain. You tag the dollar sign and it reveals the real treasure. But it also becomes the asterisk enemy immediately. Like before, odds are you will be touched by that enemy. Yeah, it sucks.

# Board 10: The end is in sight!

Testing the final board was a problem. First off, it is obvious that I hadn’t played through Water Bug II all the way. When I pulled it from tape many years ago in introduced some glitches. The board wouldn’t display as were some flipped characters. Fortunately, that was an easy fix and I soon had the board running.

Board 10 is tough due to having a lot of elements to deal with, but it isn’t impossible. The board has of split columns. There are two rotating barriers that have holes you can slip through. The enemy is here that will chase you. And, to make things more challenging, you need to hit a switch to reveal the treasure.

Water Bug II, Board 10, ZX81 Screenshot, 1984 by Steven Reid.

Right at the start, I realized the enemy wasn’t work right. It was printing numbers for its tail. The offending line was this one:

2990 PRINT AT V,I;Z

I was assuming the tail was intentional, but it shouldn’t be printing numbers. Assuming it was another tape glitch, I went back into the code to determine what it was doing. Digging into the code, I found the following lines:

3020 PRINT AT V,I;
3030 LET Z=PEEK (PEEK 16398+256*
PEEK 16399)

Seeing that, it dawned on me that I was using Z to capture the enemy tile it started on. On this board, the enemy could move through the barriers and I didn’t want it to clear them. What I needed to do was change the line to this:

2990 PRINT AT V,I;CHR$ Z

This would print the tail correctly as the enemy moved, during that any of the blocks are placed back in the board as before. Kind of a neat trick actually, but not that nice. The board is already a bit tight to maneuver around. I corrected the code and got back to playing.

After a few tries, I was able to navigate down and grab the switch. It was tough getting back to the treasure as the enemy tails you pretty close and those barriers are a bit of a pain. Although difficult, it wasn’t impossible. I actually like this board, even if I struggled to clear it.

# Summing up the game.

Besides the impossible tasks I ran into before, Water Bug II is actually a pretty innovative iteration on the first game. Even so, it needs some work as well. Adding lives and the ability to replay boards would be good suggestions for this version as well. The two impossible boards really need some work. They aren’t bad, just need the difficulty brought down just a little.

Water Bug II, Board 10 Ending, ZX81 Screenshot, 1984 by Steven Reid.

That is the one thing that irked me with my earlier games. Since humans have a limit, many games just would increase difficulty beyond most human reaction. Water Bug does a great job of being challenging with the randomness of the game. Water Bug II tries to be a harder version which lands a bit flat. Some boards are nearly impossible and that isn’t a recipe for making a game fun.

# Wrapping things up.

Playing the game again gave me a chance to revisit Water Bug II’s code. Although better than what I wrote in Water bug, it has similar problems. I do checks in the wrong order. The scoring is broken. I still have a lot of repetitive code. The game could be a lot smaller with some restructuring and a little polish.

Now I did learn that the GOSUB routine scans from the top of the program. For Water bug II, I moved the routine for testing movement to the top. That speeds up the program a bit given how long it is. It is noticeable against other games of mine and something that surprised me. Something I’ll keep in mind for future development.

Overall, Water Bug II is a well balanced game and the core play is there. It eases into the difficulty, adds in some tense game play, and then gives you a breather. Given the era and my age, it isn’t a badly designed game. With some thought, it wouldn’t be hard to make the game as fun as it is interesting.