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Title Battle Squadron
Game Type Shoot'em up
Players 1-2
Compatibility OCS/ECS
HD Installable No
Submission Klaus Dreyer

Review
This action packed game is just as traditional as it is good. Nothing new
under the sun here, maybe except for the perfect graphics, the excellent
tunes and sounds and a gameplay that'll make you sit in front of your
computer for a long time, that is if you like scrolling shoot'em'up games
of course.

The scenery is (as so many times before) space, and everything is seen from
above. The playfield is a bit wider than the screen itself, meaning that
the nice backgrounds (planet surfaces, aliens, big buildings, etc.) also
scrolls from left to right or the other way around according to the
position of your spacecraft. If you are two players you can play
simultaniously.

When you shoot down certain enemies, they drop a token that gives you more
and better fire power, and of course there's the obligatory end-of-level
monsters you have to destroy. Also, there is the opportunity to fly down
to a sublevel, but the mission is the same: Kill the aliens. The more
levels you play the harder the game gets. Nothing new here, but it's all
so very well done. The colorful and well drawn graphics and the great
sound really helps to create a new dimension for the old-fashioned
gameplay; the "game over"-tune is especially superb in all its simplicity.
If you like old-style 2D action games this is certainly the game for you,
if not play it anyway just to experience the technical side of it and the
atmosphere.

Did you re-use the basic game engine from Hybris for Battle Squadron, or did you pretty much have to rewrite the entire thing?

The design of BS was fundamentally different that Hybris. Some of the code was however re-used.

Was the 2 player mode something you decided early on or were you given feedback about Hybris lacking the 2 player option?

We knew from the beginning that we wanted 2-player. That would be the primary upgrade from Hybris. This of course included left/right scroll, and numerous other enhancements...

The amazing Predator effect where the enemy appears to be almost invisible - can you describe how that was done on the Amiga? (I can only guess that it's some blitter trick and you're shifting the shape of the baddie background sideways a pixel or two or something!)

Yes, it is using the blitter. It takes the data from the background (from the old position) and puts it into a buffer, and then reprints this buffer on the new position using the mask of the enemy... Now I actually wonder if it could have been done in one step, but there might have been issues in shifting the bits differently for the source and destination - got a bit rusty on the Amiga hardware over the years ;-)

In the intro it sounds like it's speaking "Welcome to Battle Squadron" - is that actually a (very small?) speech sample or is your brain filling in the speech guessing that's what it's saying?

It is indeed a sample. Ron Klaren must have sampled it... quite brilliant move ;-)

The end screen states it took 8 months to write the game. Did you know early on approximately how long it would take or you were given that as a deadline?

We did not really plan how long it would take at the beginning, though from previous experience we of course had an idea that it might be about a year. It was only when the game was about halfway done that it became relevant with deadlines and that sort of thing.

Were you still at school at this stage? The end screen says you were 18 years old. Or had you finished by then?

I was still in school, last year of high school, which is 3 years in Denmark.

Are there any technical tricks you were especially proud of in this game over Hybris?

Technically, BS builds on Hybris, but of course with some major improvements. To have bigger and more colourful enemies in BS we switched from sprites to bobs. This had the negative effect that we had to go down in frame rate from every frame to every second frame (for the enemy bobs, not the sprites).

It was still necessary to be clever about the time required to print the bobs, so when the raster was about 1/3 down the CRT, enemies in the top part of the screen stared being erased and reprinted. Then when the raster was 2/3 down, more enemies could be erased/printed. When the raster was below the bottom of the screen all enemies could be deleted/printed.

This avoids having to use double buffering, while still having about 1.5 frames to delete/print the bobs. Overall this saves a lot of processor time... that in turn could be used to have more enemies on the screen :-)

Most of the enemies in the game require multiple hits to kill (at least with the default weapon). Was this a deliberate choice to force the player to go for weapon upgrades or simply to make the game more difficult?

It was mostly to make the game more difficult. It would be too easy if all enemies just required one missile ;-)

Did you get much feedback about the difficulty level of the game? Could the two of you sail through it easily?

We of course got a bit of feedback here and there, but the whole process was mostly run by Torben and myself. At the time I could easily "sail" through the game... multiple times ;-)

The Predator effect was amazing, yet I can't think of another game on the Amiga that used it! Do you know of any other games that copied your effect? It seems to be one of the most widely remarked upon things in the game!

Yes, it was of course one of the major new enhancements compared to Hybris. Surprisingly, I don't know of any other games that did something similar. One things we talked about later, was that maybe we could have used the effect a bit more, to integrate it a bit more in the gameplay... but maybe we will still have a chance later :-)

For those of us that aren't programmers, can you describe the overall steps that are going on every 50th of a second? (eg. read joystick, move all baddies, sort them into Y coordinate order, restore backgrounds behind all blitted baddies, save backgrounds behind current positions, copy into copperlist etc). I'm not sure many people appreciate all the steps the programmer has to do the "old" way where you did not have the CPU power to redraw the entire screen every update like on modern hardware!

Well, you describe it very well in your question already :-) I have put a small excerpt of the code below. I guess it's pretty obvious what most of the calls do ;-) I had the "idea" to just use caps (for simplicity... maybe not wise after all...) and that all labels should be 6 letters (towards the end I had to extend to 7).

Another similar, yet more complex piece of code handles the the "other frame" where the enemies are deleted/printed... and background scrolled. I used a lot of numbering for labels... to avoid having to come up with new names all the time. VIDxxx is short for "videre", which is "onwards" in Danish. It was kind of a sister label to LOOPxx that I also used ;-)
JSR TSTJOY
BSR TSTFIR
BSR FADERS
BSR MOVPLY
BSR MOVMIS
BSR SMARTB
BSR MOVBUL
VID616: BSR STRSPR
JSR LISTER
BTST #1,COUNTR+1-VARIBL(A5)
BNE.S VID113
MOVE.L #PL1DAT,PLYCHK-VARIBL(A5)
MOVE.L #SCO1UP+8,PLYSCO-VARIBL(A5)
BRA.S VID114
VID113: MOVE.L #PL2DAT,PLYCHK-VARIBL(A5)
MOVE.L #SCO2UP+8,PLYSCO-VARIBL(A5)
VID114: BSR CHKMIS
BSR CHKGRO
BSR CHKBUL
BSR CHKCOL
BSR PRISCO
BSR ENTNAM
TST.W LISCNT-VARIBL(A5)
BNE.S VID617
CMP.W #1500,DEMCNT-VARIBL(A5)
BGE.S VID617
BSR RASCOL
BSR FLASHR
BSR ROLBUL
VID617: BSR CONBUL
BSR CHEMOD

The game doesn't seem to be running via the vertical blank interrupt unlike Hybris! The VBL only kicks in when you fly between the top and bottom parts of the map and when you die. What was the reason for this? Was there some efficiency gain doing it this way or something?

Actually, only the music runs solely as interrupt, in both Hybris and Battle Squadron. For the general code there is a good deal of "waiting for the raster" in both games...

Were there any easter eggs, secrets or bugs that made it into the game?

There is nothing hidden in BS, besides the cheat mode activation. We simply did not have time at the end. There is a small bug in BS that started happening towards the end. Sometimes one of the colors in the palette would be changed... to black if I remember right. I never did figure out what this was... but it also was very rare... maybe it is gone :-)

You worked with Ron Klaren and Ivo Zoer for the sound/music. What was it like working with them and what did each of them do? What specs were they given?

Yvo did the player and Ron did the music. We worked remotely since they were in the Netherlands, so we did not gain any real "working relationship". Later Yvo was in the US as the same time as me, and we had a great time :-) We did not really give any specs, except that it should not take up too much processor time ;-)

Now for a nice technical question! Do you have any idea how many raster lines the music routine took to play? How many of the Amiga's 4 sound channels did you allocate for the music?

These tests were done quickly... and more than 20 years ago ;-) If I remember correctly then it was something like 5-10% of the raster time, but not exactly the same each frame. All 4 channels are used for the music, but certain sound FX take over 2 of the channels when needed. In the new iOS version this is no longer an issue :-)

What was the most difficult thing programming-wise in the game?

There was a lot of things that required extensive tweaking to work. It's a bit difficulty to say if they were actually difficult, or just time consuming. Bugs were almost always a pain to figure out.

You chose this time to publish via Innerprise. What was the reason for this? Had Discovery already gone broke by that stage? The Hall of Light database has Innerprise listed as a developer, and a note saying that it is also known as Discovery. Is that even correct?

Discovery and Innerprise were not the same company. Innerprise was formed by a sales/marketing person who left Discovery. So you might want to update that ;-) Discovery was still in existence at the time, but I don't remember the timing of how it all went down... we were too focused on making Battle Squadron :-)

At what point was the publisher found? Was it easy to get it published after the success or Hybris?

Since we already were in contact with Innerprise it was much easier than with Hybris, but actually Hybris had not really been difficulty to "sell" either.

Did you have regular meetings with the publisher or sent discs in the mail, modem'd files and phone calls etc?

Torben and I did most of the work. Sometimes we would receive suggestions for changes, but it was very limited. We talked on the phone maybe every two weeks, Torben and I much more often ;-)

I would send the files via a 2400 baud modem. I remember one of the last versions, where the connection cut during the last second (this was an hour long process), due to a faulty wire on my phone line. This was really bad timing, since I actually thought my modem had broken...

Most reviews from the game seemed to review in their November, December or January issues (which were usually released in the month prior). Did you have to get the game finished to make the Xmas shopping list or was that pure luck?

There were timing issues like that. But I only vaguely remember how the deadlines were set to match that...

What did you guys think about the 109% mark awarded by Amiga Computing? I must admit I thought it was a misprint when I first sorted the database (as I didn't key in that entry) and couldn't believe that a game received more than 100%!)

We were of course ecstatic! 100% would have been great, but above 100%... well ;-) A few people I later talked to were actually a bit "upset", saying that it should not really be possible to get more than 100% ;-)

What made you decide to re-make Battle Squadron for iOS? Did you receive a lot of feedback in recent years or something?

It was a few things that fell into place. We had started talking about selling the game for emulators, but then thought that we might as well re-code the game ourselves ;-)

Can you describe how you went about converting the game from 68000 source to the iPad/iPod/iPhone? I presume you had to rewrite the entire game in C/C++ and convert and resize all the graphics?

I started out on a PC, since I did not have a Mac. After a couple of months I got a Mac and got it working on the simulated iPhone, and a month later actually on an iPhone. It was a bit tough at the beginning, since I had to get back into 68k assembler, and also C/C++, which had also been several years.

How difficult was the conversion process?

An initial challenge was actually to get the files transferred out of the Amiga, and to PC. I had to buy various hardware items to get this done, and get help from various fora - thanks for that :-)

On iOS the original Amiga graphics files are actually loaded into memory and converted live to OpenGL format. The game itself was converted in 5-6 months, essentially line by line. One of the things that took a bit longer than anticipated was the full implementation on iOS... but that should be easier next time ;-)

For those of you that own an iPad, iPhone or iPod Touch, you can now purchase the game directly from the App store! Considering the original game cost 25 pounds, the current price of 1.99 is a bargain!