Sabotage

Last updated: January 17, 2026

Overview

Sabotage is a fixed shooter arcade game developed by Mark Allen and published by On-Line Systems in 1981 for the Apple II computer.¹²³ In an era when the majority of action titles released for home computers either were inspired by or directly copied popular video arcade games, Sabotage stood apart as a genuinely original concept.⁴ The game places players in command of a gun turret tasked with defending against waves of helicopters, jets, and paratroopers attempting to overwhelm their position.³

The game was notable for its innovative scoring system that penalized wasteful shooting—one point is subtracted every time a shell is fired, discouraging the “spray & pray” gaming style common in arcade shooters of the period.¹⁵ This design decision encouraged skillful, deliberate aiming rather than random firing. Sabotage achieved considerable success, ranking 16th in the Softtalk Reader’s Poll Top-Thirty in 1981.⁴ The game was vastly pirated and became one of the most-played Apple II games of 1981, spawning numerous clones across multiple platforms including the well-known PC title Paratrooper.⁴⁵

Game Info

Developer: On-Line Systems² Designer: Mark Allen¹³ Publisher: On-Line Systems²³ Engine: Machine Language⁶ Platforms: Apple II¹²³ Release Year: 1981¹²³ Series: None Protagonist: N/A (player controls gun turret) Sierra Lineage: Core Sierra

Story Summary

Sabotage features minimal narrative framing typical of early 1980s arcade-style games. The player takes command of a powerful gun base with the objective of shooting helicopters and aircraft out of the air.⁶ The opposing forces have plans to sabotage your base through a coordinated assault involving aerial bombardment and paratrooper deployment.⁶

The gameplay scenario presents a defensive military situation where the player must fend off continuous waves of enemy aircraft. Helicopters and bombers fly across the screen, dropping paratroopers who descend toward the ground on either side of the turret.⁵ If enough paratroopers successfully land and build up near the base, they will overwhelm and capture it, ending the game.⁵

The tension escalates as the player must balance shooting down aircraft, eliminating paratroopers mid-descent, and destroying bombs before they reach the turret.³ The scenario creates an increasingly desperate defensive action as enemy forces mount successive waves of attack.

Gameplay

Interface and Controls

Sabotage supports multiple control methods to accommodate different Apple II configurations. Players can use keyboard controls with the D and F keys, a single game paddle, or a single-axis joystick to aim the turret.¹⁵ The game was designed around paddle controls on the Apple II, providing analog precision for turret aiming.⁷ The use of paddles or an analog joystick is recommended for optimal gameplay, though keyboard support provides accessibility for users without specialized controllers.⁴

The gun turret can swivel 360 degrees to aim at targets but cannot move from its fixed base position, making this a classic “fixed shooter” design.¹⁵ Firing is handled through a separate button or key press, launching shells upward toward the aimed direction.

Structure and Progression

The game follows a continuous wave-based structure with escalating difficulty. Enemies approach from the sides of the screen in repeating patterns:

• Helicopters and Bombers: Up to 4 can be on screen simultaneously, flying across while dropping paratroopers¹
• Paratroopers: Up to 8 can be falling at any given time, descending toward the ground¹
• Bombs: Up to 2 bombs can be active, dropped by aircraft and falling toward the turret¹
• Shells: Players can have up to 8 shells in flight at once¹

The game continues indefinitely until one of several loss conditions is met. There are no discrete levels or stages—difficulty increases naturally as the player’s score rises and enemy patterns become more challenging.³

Puzzles and Mechanics

The core gameplay mechanic revolves around the unique scoring system. Points are awarded for destroying enemies: helicopters and jets are worth 5 points each, paratroopers are worth 2 points, and bombs are worth 25 points.⁵ However, firing a shell costs the player one point, creating a risk-reward calculation for every shot.¹⁵⁴ With paratroopers only worth two points, even perfect accuracy yields only one net point per paratrooper eliminated.⁷ The score counter never drops below zero, preventing negative scores.⁵

Game Over Conditions:⁵

• The turret is hit directly by a falling bomb
• A single paratrooper lands directly on the turret base
• Three paratroopers land on each other adjacent to the turret base, forming a human pyramid
• Four paratroopers land on either the left or right side of the turret

This system creates strategic depth—players must decide whether to fire at distant targets (risking wasted shots) or wait for closer shots (risking being overwhelmed). The penalty for missed shots encourages precision over volume.⁴

Reception

Contemporary Reviews

Sabotage received positive reception upon release and was recognized as an innovative title in the crowded action game market. The game ranked 16th place in the Softtalk Reader’s Poll Top-Thirty for 1981, demonstrating strong commercial appeal among Apple II users.⁴

A contemporary review in Home Computing Weekly (Issue #34, October 25, 1983) gave the game 70% overall, with individual scores of 75% for Instructions, 70% for Playability, 65% for Graphics, and 70% for Value For Money.⁸ The reviewer G.M. noted that “the game loads and runs smoothly, with no snags. The graphics are adequate - that is, they show clearly what is happening - if not particularly inspired.”⁸

Modern Assessment

Retrospective analysis has been mixed. Data Driven Gamer rated Sabotage as “Below average” in a June 2020 analysis, with the reviewer Ahab commenting “This was fun for a few minutes, but got old fast.”⁷ However, the reviewer acknowledged the game’s historical significance in spawning numerous clones.

MobyGames user Katakis noted that “Mark Allen did a good job at making a version for the Apple II; the game was remarkable for the time, with its color graphics, smooth animation, and sound effects.”² The same reviewer observed that “Like all of their other games, On-Line Systems has done a great job at bringing arcade games to the Apple II. The quality of the game may be crap today, but it was good for its time.”²

Aggregate Scores:

• MobyGames: 67% (Critics aggregate)²
• My Abandonware: 5/5 (3 votes)⁹

Development

Origins

Mark Allen developed Sabotage as an original concept during a period when most home computer action games were direct clones of popular arcade titles.⁴⁶ Allen’s background included developing a 6502 interpreter for the Pascal programming language that became the foundation for Apple Pascal, demonstrating his deep technical expertise with the Apple II platform.⁴

The game represented On-Line Systems’ commitment to bringing quality arcade-style experiences to the Apple II, building on their reputation for action titles.² Rather than copying an existing arcade game, Allen created a unique defensive shooter concept that would itself become widely imitated.⁴⁶

Production

Sabotage was written entirely in machine language to achieve smooth performance on the 1 MHz Apple II processor.⁶⁴ The game was released in the summer of 1981, with MobyGames citing a specific release date of October 1, 1981.²⁴ The Player Missile Podcast places the initial release as March 1981.¹⁰

Development Credits:¹²³

• Designer/Programmer: Mark Allen

Technical Achievements

The game employed several notable technical innovations for its era. Graphics used hi-res page 1 only with exclusive-OR operations for rendering, allowing smooth sprite movement and collision detection.¹ The collision detection system was pixel-accurate, providing precise hit registration.¹

To achieve smooth horizontal movement, Allen created seven bit-shifted versions of each shape, allowing sprites to be positioned at any horizontal pixel location rather than being locked to byte boundaries.¹ The helicopter and bomber propellers feature animated twirling effects as the aircraft move across the screen, adding visual polish.¹

Shell movement operated at either 8 or 12 pixels per frame depending on whether the player was using steerable or non-steerable control modes.¹ The game managed multiple simultaneous objects efficiently: up to 8 shells, 4 helicopters/bombers, 2 bombs, 8 falling paratroopers, and 14 shrapnel fragments could be active on screen.¹

Technical Specifications

Apple II Version:¹²⁶

• Graphics: Hi-Res color graphics⁶
• Rendering: Exclusive-OR operations on hi-res page 1¹
• Collision Detection: Pixel-accurate¹
• Media: 5.25” Floppy Disk²
• Perspective: Side view, Fixed / Flip-screen²⁹
• File Size: 16 KB⁹
• Input: Paddles, Keyboard (D/F keys), Single-axis joystick¹⁵

Cut Content

No cut content has been documented in available research materials.

Version History

Version	Date	Platform	Notes
1.0	Summer 1981	Apple II	Initial release4
Atari Port	Unknown	Atari	Converted by AtariAge user Shamus10

Technical Issues

Technical analysis by Andy McFadden identified a bug in the collision detection code for falling bombs. At memory address $6ae0, the code uses the wrong structure size, which likely causes the collision detection to fail after the first entry in the bomb array.¹ This means that in certain circumstances, bombs after the first one may not properly register hits against shells.

A user on MobyGames noted that the score counter is displayed inside the turret graphic rather than at the top of the screen, which may cause visual overflow issues at very high scores when the digits extend beyond the turret edge.²

Easter Eggs and Trivia

• The game was an original concept at a time when most action games were arcade clones, making it unusual for the era⁴⁶
• Sabotage was vastly pirated and became one of the most-played Apple II games of 1981⁴
• The title was not re-released as a SierraVention title unlike some other early On-Line Systems games⁶
• Each bullet subtracting a point was an innovative anti-spam mechanic that influenced later game designs⁴

Legacy

Sales and Commercial Impact

Sabotage achieved significant commercial success, ranking 16th in the Softtalk Reader’s Poll Top-Thirty in 1981.⁴ The game’s widespread piracy, while reducing direct sales, contributed to its cultural impact and ensured it became one of the most-played Apple II titles of its era.⁴

Clones and Derivatives

Sabotage’s innovative gameplay spawned numerous clones and derivatives across multiple platforms:⁵⁶

Title	Platform	Year	Developer/Notes
Commando Raid	Atari 2600	1982	Direct clone5
M.A.D. (Missile Attack and Defense)	Atari 2600	1982	Clone5
Paratrooper	IBM PC	1982	Greg Kuperberg; “nearly a carbon copy”7
Incoming!	Atari 8-bit	1986	Conrad Tatge; ANALOG Computing magazine5
ParaShooter!	Apple IIGS	1989	Lane Roathe5
Night Raid	IBM PC	1992	Clone5
Parachute	iPod	2003	Preloaded on 3rd-gen iPod and later5

The most notable clone, Paratrooper for IBM PC, was developed by Greg Kuperberg (who also created PC-Man) and used the CGA 320x200 resolution with cyan/magenta/white palette.⁷ Data Driven Gamer noted that “Paratrooper is nearly a carbon copy of a lesser-known Apple II game called Sabotage, published in 1981 by On-Line Systems.”⁷

Collections

No major compilation releases have been documented for the original Sabotage, though the game remains available through abandonware archives and emulation.

Fan Projects

An Atari conversion of Sabotage was developed by AtariAge community member Shamus, bringing the game to the Atari platform from its Apple II origins.¹⁰ This conversion was discussed on the Player Missile Podcast.¹⁰

Related Publications

No official hint books or strategy guides have been documented, consistent with the game’s straightforward arcade-style gameplay that required no external guidance.

Critical Perspective

Sabotage represents an important milestone in early home computer gaming as a rare example of original game design during the “clone era” of 1980-1982.⁴ While most developers focused on recreating popular arcade experiences like Space Invaders or Pac-Man, Mark Allen created a unique defensive shooter concept that would itself become the template for an entire subgenre.

The game’s influence extended far beyond its initial success, with the Paratrooper-style gameplay becoming a recognized category that persisted for decades—even appearing as a preloaded game on Apple’s iPod in 2003.⁵ The scoring mechanic that penalized wasteful shooting anticipated later game design philosophies around resource management and skill-based scoring.

From a technical standpoint, Sabotage demonstrated what was possible on the limited Apple II hardware through efficient machine language programming and clever sprite rendering techniques.¹ The pixel-accurate collision detection and smooth animation were remarkable achievements for a 1 MHz processor.¹ While the gameplay may feel simplistic by modern standards, Sabotage earned its place in gaming history as an innovator rather than an imitator.⁴

Downloads

Purchase / Digital Stores

• Not currently available on modern digital storefronts

Download / Preservation

• My Abandonware – Sabotage⁹
• Internet Archive – Apple II Software Library

Technical Documentation

• 6502 Disassembly – Sabotage – Full technical disassembly by Andy McFadden¹

References

Footnotes

1. 6502 Disassembly – Sabotage Technical Analysis – Technical specifications, collision detection details, gameplay mechanics, entity limits, graphics implementation, bug documentation ↩ ↩² ↩³ ↩⁴ ↩⁵ ↩⁶ ↩⁷ ↩⁸ ↩⁹ ↩¹⁰ ↩¹¹ ↩¹² ↩¹³ ↩¹⁴ ↩¹⁵ ↩¹⁶ ↩¹⁷ ↩¹⁸ ↩¹⁹ ↩²⁰ ↩²¹ ↩²² ↩²³ ↩²⁴ ↩²⁵ ↩²⁶ ↩²⁷

2. MobyGames – Sabotage – Release date, developer credits, platform information, user reviews, aggregate ratings, technical specs ↩ ↩² ↩³ ↩⁴ ↩⁵ ↩⁶ ↩⁷ ↩⁸ ↩⁹ ↩¹⁰ ↩¹¹ ↩¹² ↩¹³ ↩¹⁴ ↩¹⁵

3. Wikipedia – Sabotage (video game) – Gameplay mechanics, scoring system, game over conditions, control methods, legacy clones list ↩ ↩² ↩³ ↩⁴ ↩⁵ ↩⁶ ↩⁷ ↩⁸ ↩⁹

4. Retro365 – Bits From My Personal Collection: Sabotage – Historical context, Softtalk poll ranking, development background, Mark Allen’s prior work, release timing, piracy impact ↩ ↩² ↩³ ↩⁴ ↩⁵ ↩⁶ ↩⁷ ↩⁸ ↩⁹ ↩¹⁰ ↩¹¹ ↩¹² ↩¹³ ↩¹⁴ ↩¹⁵ ↩¹⁶ ↩¹⁷ ↩¹⁸ ↩¹⁹ ↩²⁰

5. VirtualApple – Sabotage – Apple II version technical requirements (48K memory), disk format, playable emulation ↩ ↩² ↩³ ↩⁴ ↩⁵ ↩⁶ ↩⁷ ↩⁸ ↩⁹ ↩¹⁰ ↩¹¹ ↩¹² ↩¹³ ↩¹⁴ ↩¹⁵ ↩¹⁶ ↩¹⁷ ↩¹⁸ ↩¹⁹

6. The Sierra Chest – Sabotage – Engine type, hi-res graphics, original concept status, clone list, SierraVention status ↩ ↩² ↩³ ↩⁴ ↩⁵ ↩⁶ ↩⁷ ↩⁸ ↩⁹ ↩¹⁰ ↩¹¹

7. Data Driven Gamer – Games 193-194: Sabotage / Paratrooper – Paratrooper comparison, CGA technical specs, Greg Kuperberg credits, modern assessment, scoring analysis ↩ ↩² ↩³ ↩⁴ ↩⁵ ↩⁶

8. Home Computing Weekly #34 (October 25, 1983) – Contemporary review scores, reviewer comments, gameplay assessment (Note: review may cover ZX81 version by Macronics Systems) ↩ ↩²

9. My Abandonware – Sabotage – File size, user ratings, perspective classification, download availability ↩ ↩² ↩³ ↩⁴

10. Player Missile Podcast – Episode 6 – March 1981 release date, Atari conversion by Shamus, platform discussion ↩ ↩² ↩³ ↩⁴