C64 Impossible Mission Revised

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Impossible Mission Revised game data

Commodore 64 game name: Impossible Mission Revised | Release date: 2024 | Publisher: Extend | Game media type: d64 | Language: en
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About Commodore 64 Impossible Mission Revised

Impossible Mission Revised, based on the original Impossible Mission (the AUS version original).


– X ABC algorithm Random Number Generator from codebase64 inserted into the game
– at the start of the game you need to interact with the joystick 2 for added entropy in RNG start.
– the player needs to push the joy2 button and upon releasing it, the RNG seed is set with the user interaction information.
– The dummy loop wait routine changed to D012-based waiting instead of burning CPU cycles for time.
– this fixes timings with possible CPU speeders.
– The Game clock is now set with PAL/NTSC info, 1 second is 60 frames in NTSC and 50 in PAL
– The original game ran slower on PAL systems as one second was 60 frames on all versions.
– The game has PAL/NTSC detection, I used that for setting the clock tick value.
– After the game over laughter, the screen shakes and blanks to white, the screen isn’t centered and black color peeked from the edges.
– Restored default screen values after shaking.
– Added code to play samples more loudly on 8580.
– the Vice seems to distort but plays ok on real hw.
– TNT helped with proposing packing Elvin Atombender gfx
– TNT supplied packed data and unpack-routine
– 1k color info now takes only 157bytes
– File saving simplified
– The original file save was overcomplicated.
– first, it saved “HI2”, then deleted “HI” and renamed HI2 to HI
– new one uses overwrite
– IRQ and File-saving routines moved lower in memory
– saving works now with action replay active
– FC3 corrupts the screen after saving, but save works and you can restart the game using RUN/STOP, RESTORE or both.
– the time-out game over scene, bugs and features.
– the last byte of the bank is visible
– elevator sprites make the scene look broken
– the last byte of the bank is now cleared during the screen shake and restored afterward.
– the elevator wall sprite is turned off and the ceiling sprite is moving with the screen
– the scene looks now much better
– Rooms 15 and 20 were incorrectly assigned hires color to MC tiles
– Changed the color code showing tiles as MC
– This can be argued if it is a bug or an intentional choice.
– My take on this is that it was a bug, which is now fixed.
– If a room has been emptied by searching, it is hollow on the player map.
– This makes the game a little bit more comfortable to play
– this was surprisingly difficult to add
– If the player falling accelerates above a certain threshold shake the screen
– 5 frames random $d011 shake implemented
– Avoiding the last byte of the bank is needed again, I should look into skipping that byte for code.
– no sound fx for the falling thud
– there was also a bug in the original game, the falling byte wasn’t set on the death event which caused a lot of unnecessary processing of the hero.
– The game clock is now in a 24-hour format
– I don’t believe agents/military/whatever officials use am/pm time to avoid confusion.
– Note puzzle rooms are also marked on the map with a checker pattern
– Screen shake after the player falls from a high place now also moves the sprites along the screen shake. looks much cleaner now.
– Sound effect added for the floor hit.
– Also the door to Elvin’s lair is marked on the map, but you need to collect the items first.
– Sprite clock code is done, it shows hours and minutes.
– displaying the clock on the playfield is another pain in the butt
– I ran out of memory again.
– now more of Elvin’s end screen is packed
– large code blocks moved under IO which are mainly responsible for randomizing the game on init.
– The game now has 32 different passwords
– One gets chosen randomly on the game start
– The game clock is now rendered in characters in normal rooms
– the clock is at the upper right corner of the screen
– it cannot be shown when a player is searching for items as it uses the same characters.
– it cannot be shown in note puzzle rooms, as the GFX uses the same characters.
– it doesn’t show up in the elevator room, as you can activate the clock by pressing the fire button.
– New bot animation frame sprites by Trurl
– you can now see the backside of the bot if the game randomly chooses so.
– it was a true pain to add these, the game had its own logic tuned pretty hard into just 6 frames of robot animation, peeking etc..
– we have now a total of 12 frames of robot sprites, and still have some memory left!
– a lot of problems caused here, I hope I fixed them all which I caused myself.
– Fixed a color bug in the phone user interface from the “orientation corrected” message.
– 32 passwords were a little too much, back to only 24 which will fit in one page of memory.
– Excellent suggestion from a test user the wolf from the lemon64 forums
– make the clock run from 12:00 -> 18:00 so the semicolon can be fitted cleanly.
– There are 2 characters of space, 16 pixels in total.
– Number font is 3×5 pixels and when you want to show 4 digits, it takes 3+1 pix (we want to have some space between digits)
– 4*4 digits is 16 pix, so no room for a semicolon.
– We can LSR the last 2 digits to get 2 pixels of space between hours and minutes.
– Number 1 is special because it’s just 1 pixel wide, so if we ASL hour digits also we can have a 3 pixel wide gap for the semicolon.
– Usually, the simple solution is the best, too bad it’s often hard to come by yourself when you are fixated on thinking about something else.
– Preparing to change in-game Commodore ROM font to something else
– a to z and 0 to 9 needed
– The font called 7-up from https://home-2002.code-cop.org/c64/ is selected into the game.
– Extra robot sprites moved to even Sprite Pointer number
– The game uses the first bit of the pointer when peeking behind its back
– An uneven pointer number caused me some days of pain because I wanted to save 64 bytes.
– Modified puzzle stencils to change the challenge with the puzzles
– done, more challenge added
– Fixed score calculation to calculate seconds on 0-6 hours instead of 12-18.
– A small cosmetic change to the char clock shown in the rooms.

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Impossible Mission Revised C64 keyboard mapping

When you start a game, each joystick port is automatically turned on. Sometimes this causes a problem as the joystick port is mapped to the keys below. If a game uses these keys, you need to turn off the joystick ports.

C64 emulator joystick - keyboard mappings