Flicky (1984)

I’ve been digging around in the MAME source code to learn a bit more about Flicky. Apparently, there are two versions of the game. Which would go towards explaining why I found my arcade machine easier to play than the version I had chosen to play in MAME!

The original version is easily identifiable as it displays a screen showing at which scores bonus lives are awarded during the attract loop. This is the version in my arcade cabinet. MAME refers to this as flickyo.

The alternate version doesn’t have the bonus lives screen and is noticeably more difficult. MAME refers to this as flickys1.

To add to the confusion these versions also exist for System 2 hardware, making a total of four different versions of the game. MAME refers to these extra System 2 versions as flicky and flickys2.

The alternate System 1 version, flickys1, has an odd extra feature—an option to have sound effects play during the attract mode, enabled through the DIP switch settings.

Whilst moving in my cab, I found a couple of Aladdin’s Castle arcade tokens. It’s hard to say for sure, but I suspect that my Flicky cab spent a period of it’s life at one of America’s finest shopping mall video game arcades.

I’d love to know more about the history of my machine, but fear the facts have been lost to the ravages of time. If you know different, please get in touch.

As is typical for games from the era, Flicky uses the inexpensive Zilog Z80 microchip. In fact, it uses a couple of them. The Z80 the same chip that was found in the Sinclair ZX Spectrum, Nintendo Game Boy and some other home computers, arcade machines and electronic devices made in the 80s.

Since the Z80 is so old it is also extremely well understood. I plan to use this knowledge to my advantage and take a look inside the Flicky game code. This sort of reverse engineering process is called disassembly - where the machine code is converted back into a (slightly) more readable symbolic form called assembly language. The book above is a gentle introduction to the machine code of the Z80 (and the M6502, another common CPU from the period which was used in the Apple II, BBC Micro, Commodore VIC-20 and arcade games such as Data East’s Burger Time). The book is available for free as a 31MB PDF.

You’re probably aware of another arcade game of the same age that uses the Z80: Tehkan’s Bomb Jack. It’s another great single screen platform game which shares a few concepts with Flicky. Compared to Flicky, Bomb Jack is a more popular game. I was happy to see that Bomb Jack has already been reverse engineered. That doesn’t help understand the inner workings of Flicky, but it proves that such an endeavour is possible.

So I’ve set myself another task that, much like my high score attempt, has no real deadline: to disassemble Flicky to understand the inner workings of the game. Most notably I’d like to figure out the reason diamonds are sometimes dropped, the logic behind the behaviour of the gecko and, to a smaller degree, the cats. And then figure out a bit about the Special window bonus. My first step is to brush up on my Z80 assembly language with the help of the book above. It’s been a while.

If you have any experience disassembling Z80 code and fancy helping then please get in touch.

If you’re attempting for any sort of record, as I am, then you have to play to maximise your score. Every point counts. So here’s an overview of the scoring system, with a few notes as to where there may be opportunity to increase my ability to score. I need your help with those!

Basic Points
Pick up chick: 10
Knockout one cat: 200
Knockout second cat with same throw: 400
Knockout gecko: 400

Diamonds
Pick up diamonds to collect extra bonus points.
Value: up to 3000?

I’d love to know more about what governs the behaviour of diamonds. Their point value might be coupled to some sort of counter, perhaps related to the total number of diamonds dropped so far in the game. But what makes a cat drop a diamond (or not) after being knocked out? I need to know.

Exit Points
If you take multiple chicks to the exit you get bonus points:
1st chick: 100
2nd chick: 200
3rd chick: 300
4th chick: 400
5th chick: 500
6th chick: 1000
7th chick: 2000
8th chick: 5000

Time Bonus
If you finish the round quickly you get bonus points.
0-19: 20000
20-29: 10000
30-39: 5000
40-59: decreases with every second
60+: no bonus

Bonus Round
Score: (chicks caught) * 250
Perfect bonus: 10,000

Extra lives
Obtain extra lives as your score passes:
30,000
80,000
160,000

Window Bonus
Approximately every six levels, starting at level 10, if you are scoring well a character will appear in the Special window on completion of the round. This has the effect of causing your end of round bonus points to be multiplied by a factor that increases the further you get into the game, resulting in the possibility of exponential score increases. Suffice to say this is the key to world record scores, so I really want to figure them out some more if I can.

Help?
If you can help shed any light on the scoring system, please get in touch.

This post will likely be in a state of flux as I figure out the finer details of the bonus system.

Key
1: Current player number
2: Current score
3: High score
4: Exit
5: Good chick
6: Bad chick
7: Flicky
8: Cat
9: Throwable item
10: Normal windows
11: Air vent
12: Special window
13: Platform
14: Lives
15: Current round number