Why does this game look like Keen?

This is where you can post your Commander Keen related stories, artwork, or other stuff that is related to Commander Keen but otherwise doesn't belong in another forum.
Post Reply
User avatar
XrackProject
Vortininja
Posts: 73
Joined: Thu Nov 03, 2016 19:10
Location: Earth
Contact:

Why does this game look like Keen?

Post by XrackProject » Sat Jan 20, 2018 20:24

Hey friends,

I just found this video on Youtube: Secret Agent

Why is this game looking like Keen1-3 ?! I have never seen this game before. Do you know this one? Is it worth to play?
A project for lifetime.

User avatar
Nisaba
Vorticon Elite
Posts: 822
Joined: Fri Jan 01, 2016 23:34
Location: The Outpost
Contact:

Re: Why does this game look like Keen?

Post by Nisaba » Sat Jan 20, 2018 20:59

nice find, reposted it over here: viewtopic.php?f=2&t=4024&p=86882#p86882
"We have come to conquer you all and bring you lots of candy!" | about me | my current project: play Keen mods on a GameBoy |

User avatar
Lunick
Vortininja
Posts: 267
Joined: Tue Jun 01, 2010 10:37
Location: Melbourne, Australia
Contact:

Re: Why does this game look like Keen?

Post by Lunick » Sat Jan 20, 2018 21:26

If you like Secret Agent then you will like Crystal Caves too
Lunick is Here

User avatar
XrackProject
Vortininja
Posts: 73
Joined: Thu Nov 03, 2016 19:10
Location: Earth
Contact:

Re: Why does this game look like Keen?

Post by XrackProject » Sat Jan 20, 2018 21:27

Someone in the comments of this video mentioned that its a Commander Keen clone? According to the Titlescreen of this game its not from ID-Software.
A project for lifetime.

User avatar
K1n9_Duk3
Vorticon Elite
Posts: 472
Joined: Mon Aug 25, 2008 9:30
Location: Germany
Contact:

Re: Why does this game look like Keen?

Post by K1n9_Duk3 » Sat Jan 20, 2018 22:24

Secret Agent is a smooth scrolling platformer from Apogee, much like Commander Keen (and even more like Crystal Caves) but that's about it. I guess it's the same story as with most of the early first person shooters, which were often referred to as "Doom clones". But I can also remember people comparing Secret Agent to Duke Nukem ... probably because of the haircut of the main character sprite.

Just to get this potential misunderstanding out of the way: Secret Agent and Crystal Caves do not use any code from Commander Keen. They use the ProGraphx Toolbox for most of the low-level graphics stuff. This toolbox was created by Peder Jungck (the author of Secret Agent) and earlier versions of the routines were used in Dark Ages, Duke Nukem and a few other games. See http://legacy.3drealms.com/news/2006/04 ... cy_15.html and http://www.shikadi.net/moddingwiki/ProG ... set_format for further information.

What I find interesting about Secret Agent and Crystal Caves is the fact that these seem to be the first EGA games on the PC that can actually move images by 1-pixel increments around the screen. In all the Keen games, the sprites always move by at least 2 pixels.

P. S.: If someone wants to be a smartass, feel free to leave a comment on that video, pointing out that the screen flash mentioned in the video description occurs when you destroy the sattelite dish, not when you take damage. At least that's how my version works.
Hail to the K1n9, baby!
http://k1n9duk3.shikadi.net

User avatar
MoffD
Vorticon Elite
Posts: 1169
Joined: Thu Jul 05, 2012 17:30
Location: /dev/null
Contact:

Re: Why does this game look like Keen?

Post by MoffD » Mon Jan 22, 2018 13:54

Oh yeah, I played Secret Agent along with Keen. Both are unique in their own way.
Secret Agent's smaller tiles compared to jump height etc... make platforming a little interesting in it, but definitely a good game. I like jumping better in Keen, but secret agent has some neat stuff like barrel pushing puzzles and enemies with interesting hitboxes/stages

Edit: DOOT DOOT DEET DEET DOOT
mortimermcmirestinks wrote: Now I wish MoffD wasn't allergic to me.
Levellass wrote:You're an evil man.
Image

User avatar
KeenRush
Android Dummy
Posts: 2540
Joined: Sat Oct 27, 2007 20:57
Location: KEEN1.EXE
Contact:

Re: Why does this game look like Keen?

Post by KeenRush » Thu Jan 25, 2018 10:07

Honestly, I don't understand how you can find any similarities whatsoever in these games - other than that you can jump and shoot in them. :) Also, I'm surprised you didn't know this game already, I thought it was quite a famous platformer. (I might be wrong about that though.) Having played this and Keen a lot as a kid, I can recommend this one (and Crystal Caves). Worth playing. I should play it again myself. Seeing that island gets me nostalgic. I still think it's some gorgeous world map design.

@K1n9_Duk3: Interesting, re: speed. I can't be 100% sure right now because I don't feel like testing, but I think that's just because stuff is fast - I think I've had things crawling by 1-pixel increasements when I've altered stuff and made things move in slow speeds. I don't think there's any engine limit.
My newest mod - Planet Of Agony: https://pckf.com/viewtopic.php?t=4165 | codename H.Y.E.N.A.

User avatar
K1n9_Duk3
Vorticon Elite
Posts: 472
Joined: Mon Aug 25, 2008 9:30
Location: Germany
Contact:

Re: Why does this game look like Keen?

Post by K1n9_Duk3 » Thu Jan 25, 2018 22:07

KeenRush wrote:
Thu Jan 25, 2018 10:07
@K1n9_Duk3: Interesting, re: speed. I can't be 100% sure right now because I don't feel like testing, but I think that's just because stuff is fast - I think I've had things crawling by 1-pixel increasements when I've altered stuff and made things move in slow speeds. I don't think there's any engine limit.
Maybe I should have mentioned that earlier: I'm talking about single-pixel movement in x-direction (left/right). Single-pixel movement in y-direction (up/down) is the easiest thing in the world for EGA and VGA video modes.

From what I've seen so far, all Keen games create "shifted" versions of the sprites when the sprites are loaded, and they never create more than 4 versions of the sprite. This is actually why the EGAHEAD files in Keen 1-3 have four entries for every single sprite. To be able to move the sprite in single pixel units, the Keen games would have to keep 8 different versions of the same sprite in memory. By using multiples of 2 pixels instead, the memory requirement is cut in half. Example: The EGASPRIT.CK1 file is 17.2 kB. 4 shifts (movement in multiples of 2 pixels) mean the game needs at least 68.8 kB to store all the sprites. For 8 shifts (1-pixel movement) the game would need at least 137.6 kB to store the sprites. It only gets worse when you move on to Keen 2 & 3.

Crystal Caves and Secret Agent don't do this. They do the shifting while drawing the tile, which doesn't require any additional memory, but makes sprite drawing a bit slower (compared to Keen).

If I'm not mistaken, Axtroxian Realm (and perhaps other mods) use modified sprite drawing routines that are able to perform the shifts on-the-fly while drawing the sprites, thus freeing up memory for other things. But the default behavior in all the Keen games is to trade some memory for faster drawing.

Most of the time, you won't even notice the difference between 1-pixel movement and 2-pixel movement anyway. You can notice this in Keen 1-3 when Keen is standing on a platform that moves left or right, or when jumping left/right while the cemra is also scrolling. You'll see the sprite moving back and forth by 1 pixel because the engine is unable to to draw the sprite where it would actually need to be drawn. Keen 4-6 "fixed" this by making sure the camera always scrolls by multiples of 2 pixels in x-direction, and I think the platforms also move by 2 pixels in the later games.
Hail to the K1n9, baby!
http://k1n9duk3.shikadi.net

User avatar
KeenRush
Android Dummy
Posts: 2540
Joined: Sat Oct 27, 2007 20:57
Location: KEEN1.EXE
Contact:

Re: Why does this game look like Keen?

Post by KeenRush » Fri Jan 26, 2018 8:00

That's very fascinating, thank you. Clearly I was out of my depth here. :helmet Glad to have more knowledge of the engine! It seems it's something I've just not noticed properly. Hmm, what about this test case: Keen sprite has a collision block of x pixels wide. x is an even number. Then the collision block's width is changed to x-1. Running against a solid wall, will Keen be displayed in the exactly same position as before, even if he should be one pixel further because the collision box is smaller? (I guess yes, but just asking.)
My newest mod - Planet Of Agony: https://pckf.com/viewtopic.php?t=4165 | codename H.Y.E.N.A.

mills
Meep
Posts: 1
Joined: Wed Jan 24, 2018 22:49

Re: Why does this game look like Keen?

Post by mills » Fri Jan 26, 2018 15:10

Secret Agent runs a lot slower than keen games it surelly uses another engine, it looks similar but it is not as smooth as keen. Also is very difficult to land in tiny platforms :).

User avatar
K1n9_Duk3
Vorticon Elite
Posts: 472
Joined: Mon Aug 25, 2008 9:30
Location: Germany
Contact:

Re: Why does this game look like Keen?

Post by K1n9_Duk3 » Fri Jan 26, 2018 21:45

KeenRush wrote:
Fri Jan 26, 2018 8:00
will Keen be displayed in the exactly same position as before, even if he should be one pixel further because the collision box is smaller? (I guess yes, but just asking.)
I'd say yes, but that's just my guess. You shouldn't have much trouble modifying the sprites and adding a patch to run a quick test. Just keep in mind that even though it might look like the sprite is still 1 pixel away from the wall, the object might already be touching the wall.

@mills: Here are some facts that back up what you said: Secret Agent is limited to about 18 frames per second. Keens 1-3 run at up to 24 fps and Keens 4-6 (plus Dreams) run at up to 35 fps. Secret Agent is actually locked at 18 fps while the Keen games can adapt to different frame rates. If your CPU is too slow to achieve the full fps, the framerate in the Keen games will drop without actually slowing the game down (at least to some degree). Since Secret Agent can't do that, it had to be locked at a rather low frame rate so that the slowdown would appear less frequently (and would also be less noticeable).

Long story short: On slow systems, it is possible for the Keen games to run at 18 fps or less. Secret Agent may or may not run faster on the same system. (It'll probably be slower.)
Hail to the K1n9, baby!
http://k1n9duk3.shikadi.net

User avatar
KeenRush
Android Dummy
Posts: 2540
Joined: Sat Oct 27, 2007 20:57
Location: KEEN1.EXE
Contact:

Re: Why does this game look like Keen?

Post by KeenRush » Sat Jan 27, 2018 8:18

I was curious enough and found the required energy to do the one minute sprite edit. I started normal version and ran against a wall and took a screenshot. Then I shaved off a pixel from the collision box width, imported the edited running frames, and ran against the same wall, took a screen. Zooming in both and comparing them, Keen's placement is pixel perfect identical. So yeah, it's as assumed. The world I thought I knew, is no more. :bloody
My newest mod - Planet Of Agony: https://pckf.com/viewtopic.php?t=4165 | codename H.Y.E.N.A.

SpeightM09
Grunt
Posts: 7
Joined: Wed Oct 25, 2017 18:49

Re: Why does this game look like Keen?

Post by SpeightM09 » Sat Feb 17, 2018 4:55

Ah yes I remember Secret Agent. Me and my sister used to love those games almost as much as Commander Keen (not as much obviously, we're not monsters) i think one of the original Vorticon trilogy teddy bears was in there somewhere?

Kayburt
Grunt
Posts: 15
Joined: Tue Jul 17, 2018 12:51

Re: Why does this game look like Keen?

Post by Kayburt » Tue Nov 27, 2018 10:46

The elements that Secret Agent and Commander Keen have in common are:

1. The Teddy Bear item
2. Flat platforms with no grabbing ledges
3. Vital points to destroy (Satellites in Secret Agent, Tantalus Rays in Keen 2)
4. Two different game modes. Overworld mode and platform game mode.
5. A lot platforms made of square blocks (Keen 3 mostly)

Post Reply