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ID Category [?] Severity [?] Reproducibility Date Submitted Last Update
05725 Gameplay Major Always Oct 12, 2014, 19:46 Apr 14, 2021, 23:18
Tester Arkhound View Status Public Platform MAME (Official Binary)
Assigned To furrtek Resolution Fixed OS Windows Vista/7/8 (64-bit)
Status [?] Resolved Driver
Version 0.154 Fixed in Version 0.231 Build
Fixed in Git Commit c1bf2b9 Github Pull Request #
Summary 05725: contra and clones: Rolling mines behavior is inaccurate.
Description I noticed that while playing Contra on MAME, the rolling mines launched by certain enemy soldiers during the 3D base stages have a tendency to roll towards the lower right corner of the corridor. Yet, in all the gameplay videos on Youtube that have the game running on the actual PCB shows the rolling mines being spread out instead.

Skip to 1:00.

Skip to 1:40.

Now here's Contra running on MAME (skip to 1:20)

It's possible that the enemy A.I. behavior during the 3D stages might not be emulated correctly.
Steps To Reproduce
Additional Information I played every Contra set currently emulated by MAME and the only version where the rolling mines behave differently is in Gryzor set 2 (gryzora), where the rolling mines will be directed towards the direction the player is standing. Gryzor set 2 seems to have other weird differences with the other sets (notably Bill and Lance "bleed" when they're killed while swimming in Stage 1).
Github Commit
Regression Version
Affected Sets / Systems contra and clones
Attached Files
png file icon 0000.png (17,454 bytes) Nov 9, 2014, 19:37 Uploaded by Augusto
There are no relationship linked to this issue.
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Oct 12, 2014, 23:32
Without testing, I think of 2 possibilities:
1) Difficulty settings might be different from game to game
2) The MAME video shows 2 player simultaneous. Some games will increase difficulty when more players are playing. The moving barrels towards a certain person might be an indicator of this.
Flagged as possible
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Oct 12, 2014, 23:45
edited on: Oct 12, 2014, 23:46
I played the main Contra set by myself in every possible difficulty setting (from Easy to Hardest) and the mines always roll towards the right corner.
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Oct 12, 2014, 23:51
Fair enough.. just some thoughts before trying to confirm.
I can confirm the observation that the barrels rolling at you in the 3D stage do not roll straight down on MAME (parent set tested).
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Oct 13, 2014, 00:04
All the versions of Contra seem to behave the same way except Gryzor Set 2. In Gryzor Set 2, the rolling mines (as well as the second wave of enemy soldiers in each corridor) always direct their aim at the player.
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Nov 9, 2014, 19:32
edited on: Nov 9, 2014, 19:40
Have another strange detail in 3D stages with the rolling mines. See the image file 0000.png. If the player destroy the device that power off the eletricity allowing to progress to another scene and the player character jump exactly in moment that the device was destroyed have chance of lose an life if is in same horizontal line with the mines because the mines are destroyed, but the player character not is close with the mines. This is random.
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Nov 21, 2015, 20:12
I decided to revisit this report and noticed that the two roms unique to Gryzor Set 2 (g2.18a and g3.17a), which is the versions where the rolling mines act differently on MAME, are not named like the equivalent sets (which have names like i02.18a and i03.17a, j02.18a and j03.17a, k02.18a and k03.17a, ect.) Could it be some kind of modded version?
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Nov 24, 2015, 06:53
this game shows (NO GOOD DUMP KNOWN) when you audit it in the last versions of mame so maybe is not a bug but the rom itself
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Senior Tester
Aug 23, 2019, 20:07
edited on: Aug 23, 2019, 20:18
I think the "possible" flag should be removed in this report. This is a legit bug with evidence from several pcb videos.
Another video of Luke Morse contra pcb. Yeah, the mines do not behave as in mame
2:09, 4:38,

Another pcb here. Mines behaving the same as in the previous video in 1:42
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Aug 24, 2019, 06:31
edited on: Aug 24, 2019, 06:34
Checking this behaviour, enemies shoots to the right side too, including the mines, happen in all sets
Other detail:
Only happen when the enemies moves from right to left and shoots only to the right side, if the enemies moves of left to right, the enemies shoots ok
Too happen: when the mines are shoots the bullets go the same direction

PS: happend in all sets
PS2: Not happen in NES/Famicom, the "3d" levels has the same detail from the mines and bullets (1 way direction and and follow bullets)
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Senior Tester
Oct 8, 2019, 20:42
This comparison video I've uploaded proves perfectly what Fortuna said in the previous message:
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Oct 10, 2019, 16:01
I suspect this problem may have something to do with not emulating the 007452 math chip.
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Senior Tester
Apr 13, 2021, 06:30
edited on: Apr 13, 2021, 06:30
Pull request to fix this by Furrtek: