Parallaxian: Collision & Flight Physics

1 February 2023 · Updated 26 February 2026

Ground Collision Detection

Detection routines for surface-level obstacles were built by modifying the existing aerial collision code to account for terrain geometry stored in the scrolling layer data. When the aircraft strikes solid terrain elements, destruction is triggered, accompanied by a screen-shake parallax effect that creates smoother visual transitions than an abrupt explosion. The shake effect temporarily offsets all parallax layers, creating a visceral impact sensation while hiding potential sprite repositioning artifacts.

The collision system samples terrain height from character data rather than pixel-level detection, providing adequate precision while maintaining performance. Fine-tuning the collision boundaries required extensive playtesting to balance challenge with fairness.

Flight Mechanics

Development efforts concentrated on automated launch and touchdown sequences that bookend missions. The vertical landing mechanism employs an automatic thrust management system that cuts lift engines upon detecting proximity to the ground, enabling gravity-assisted landings cushioned by suspension damping in the landing gear animation. Plans exist to revamp these mechanics for increased player control, taking cues from retro gaming classics like Thrust and Oids where fuel management and momentum create emergent challenge.

The current system prioritizes accessibility, automatically handling complex maneuvers that might frustrate casual players. Future difficulty modes may expose these systems to manual control for players seeking deeper engagement.

Visual Systems

Additions include articulating engine nozzles for dynamic geometry rendering that responds to thrust direction and speed brake animations visible during rapid deceleration. Graphics data streams dynamically through the primary game loop to reduce memory usage while enabling independent animation systems—each visual element maintains its own frame counter rather than sharing global animation timing.

This streaming approach enables more animation variety than would fit in static memory allocation, though it requires careful scheduling to avoid visible pop-in during high-action sequences.

Gameplay Features

Players can exit the cockpit for ground-based exploration, transforming the game from aerial shooter to side-scrolling action temporarily. The pilot sprite utilizes powered exoskeleton mechanics for augmented jumping ability, necessary for traversing terrain and reaching survivors in elevated positions. Rescue operations reminiscent of Choplifter form a core gameplay pillar, requiring players to balance combat effectiveness with humanitarian objectives.

A key limitation: the Figment aircraft seats only two, restricting passenger transport to one person at a time. This constraint creates interesting strategic decisions about rescue order and route planning through hostile territory.

Technical Challenges

RAM limitations necessitated extensive optimization work, including reevaluating VSP (Variable Screen Position) scrolling approaches and merging explosion animation handlers that previously maintained separate memory pools. The 64KB address space forces constant trade-offs between visual variety and gameplay complexity.

Memory profiling revealed several routines storing intermediate calculations that could be recomputed on demand, trading CPU cycles for precious RAM bytes. These micro-optimizations accumulate into meaningful capacity for additional content.

Next Priorities

Control scheme refinement based on beta tester feedback regarding responsiveness and input latency
Momentum effect enhancements making the aircraft feel appropriately weighty without sacrificing maneuverability
View tracking adjustments to keep the action visible during high-speed chase sequences
Hunter-Killer enemy AI upgrades with missile systems that create sustained threat requiring evasive maneuvers

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