Full Vibe-Code (AI generated almost all game code)
Assets & Pipeline Involvement
Build tools / Asset conversion scripts
Project Notes & Prompts
Claude
Gryzor (Ocean / Konami, 1987) is the Amstrad CPC adaptation of Contra. The game looks great, but the background never truly scrolled; instead, it advanced in half-screen jumps, pausing briefly each time.
CONTRA 6128 is a reworked version of the original game for the Amstrad CPC 6128, featuring smooth, continuous background scrolling.
What has changed
Continuous scrolling in the jungle and final level: the background follows the player instead of jumping by half-screen increments.
Smooth waterfall ascent: the original’s one-third-screen jump is replaced by an animated upward movement.
No more pausing at screen transitions.
Clean display: each frame is prepared off-screen and then displayed instantly.
New title screen and title: CONTRA.
What remains the same
The graphics, enemies, rules, and game pacing are identical to the original.
The fixed-screen levels (base corridors) are exactly the same as in the 1987 game.
The original music from the 128KB version is included: press ESC at the title screen to switch between sound effects and music.
Wow, Gryzor is such a landmark in the CPC world. Having an AI modifying it with only prompting is a huge demonstration of its progress.
No more pausing at screen transitions.
There were big steps, obviously, but there never was a real “pause” IMHO: the gameplay remained “smooth” to me (in the sense of no wait). Sure the big step on each screen change meant you had to somehow know in advance where you’ll land, but still there’s overlap and that’s the kind of limitation we accepted at that time, especially given the whole game was kind of flawless besides.
Impressive feat by Claude Fable. Thanks M. Louvet for trying this and reporting to the whole world!
This update fixes gameplay issues found while playing version 1.0, and adds a jump button.
Gameplay fixes
Enemies show up on time. In version 1.0, some enemies appeared too late with the new smooth scrolling, especially the turrets built into the scenery and the bonus pods you have to destroy. Every enemy now appears at the exact moment its part of the scenery scrolls into view, at the same place as in the original game.
The flying weapon capsule is back. The capsule that flies in from behind early in the first stage, carrying the spread gun, was removed by the scrolling before it could reach the screen. It now crosses the screen as it did in 1987.
The base entrance opens again. At the end of the first stage, the destroyed door is now properly replaced by the hole, instead of the closed door reappearing.
No more missing enemies. The game only has room for seven enemies at a time. In the last stage, version 1.0 could lose one of them when that room was full; an enemy now waits for a free spot instead of being dropped.
New
Jump on the second button. The second fire button of the joystick now makes the player jump, even while firing. Pushing up still jumps as before, and up + fire still aims upwards.
Version number shown at the bottom left of the title screen.
Yeaa… that scrolling is NOT smooth, quite the opposite in fact. It’s terrible scrolling.
And when the screen is full of sprites and bullets (especially when you’ve shot your spread weapon) the frame rate absolutely tanks. Unlike the original version where the FPS was locked in.
