Comparison

Jupiter Attack vs Gem Tower Defense Mobile

Price, ratings, monetisation and update history for both games, side by side — with what reviewers say about each.

Head to head
About

Jupiter Attack

Engage in intense arcade-style space combat against relentless alien invaders. Navigate your ship using intuitive controls on Apple Watch and iPhone, collect power-ups, and aim for the highest score on the global leaderboard. Relive classic arcade action with retro visuals and sound.

Highlights
  • Bullet hell arcade action
  • Apple Watch and iOS compatibility
  • Power-up collection (multi-shot, shield, rapid fire)
  • High-score leaderboard
  • Intuitive Digital Crown controls on Apple Watch
  • Swipe controls on iPhone
  • Retro sound effects
Features
Read full description

Prepare to enter bullet hell... The 2nd in the Space Watch Trilogy, Jupiter Attack pits you against an onslaught of merciless space invaders, intent on destroying Earth! Use the Digital Crown on Watch and touch screen on iPhone to move your ship and destroy the oncoming alien menace. Collect power-ups as you compete to earn the highest score in this retro inspired arcade classic. • Playable on Apple Watch and iOS devices! • Power-ups include multi-shot, shield and rapid fire! • High-score leaderboard on Apple Watch and iPhone! • Intuitive and simple controls using the Digital Crown on Apple Watch! • Swipe to move on iPhone! • Retro sound effects on the iPhone! • Runs at 60fps on the Apple Watch! • Play anywhere, anytime! Relive the glory days of the arcade on your Apple Watch and iPhone. For the first in the Space Watch Trilogy download Kepler Attack! Thanks for playing - Johnno

About

Gem Tower Defense Mobile

Strategically place and combine gems to build mazes and towers, defending against waves of enemies. Each playthrough offers a unique puzzle with diverse gem abilities and enemy types.

Highlights
  • Build winding mazes and towers
  • Draft, reroll, and combine gems
  • Follow templates for advanced combinations
  • Discover gems with distinct stats
  • Defend against different enemy types
  • Survive 50 challenging waves
  • Retro pixel art graphics
Features
Read full description

Build the maze. Draft your gems. Survive all 50 waves. Gem Tower Defense Mobile is a retro reimagining of the classic GemTD custom-map experience, rebuilt from the ground up for touchscreens. Every gem you place is both a tower and part of your maze. Shape enemy routes, create powerful choke points, and keep each wave under fire for as long as possible. One clever placement can transform your entire defense. Each draft brings a new decision. Keep the gem, reroll it, or combine matching gems into stronger towers. Follow gem templates to work toward powerful combinations, or adapt your strategy when the pieces you need refuse to appear. No two defenses play exactly alike. Study each gem’s damage, range, attack speed, targeting, and special effects. Mix colors and abilities to cover weak points, slow dangerous enemies, and prepare for the next wave. When every tile counts, use the magnifier for precise placement. FEATURES • Survive 50 increasingly challenging waves • Build winding mazes while placing your towers • Draft, keep, reroll, and combine gems • Follow templates to create advanced gem combinations • Discover gems with distinct stats and special effects • Defend against different enemy types and threats • Use the magnifier for precise, touch-friendly building • Enjoy crisp retro pixel art inspired by classic custom-map strategy games Every run is a new strategy puzzle. Will you chase a rare combination, reinforce the maze you already have, or gamble on one more draft? Build carefully. Combine wisely. Defend the path.

Screenshots

Jupiter Attack4 screens
Gem Tower Defense Mobile4 screens

Verdict

The call

The clearest difference is review sentiment: Gem Tower Defense Mobile at 100% against Jupiter Attack's 40%. Gem Tower Defense Mobile also leads on update cadence (weekly vs every 2 months). Jupiter Attack's advantage is rating (4.5 vs 3.0) and ratings volume (393 vs 2). On ads and in-app purchases there is nothing between them.

Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS

CostPrice · In-app purchases · Ads · Monetization

Jupiter Attack costs $1.99 and Gem Tower Defense Mobile $2.99 up front. Neither carries in-app purchases, so what you see is what you pay.

ReceptionRating · Positive reviews · Number of ratings

Jupiter Attack holds the better App Store score, 4.5 against 3.0. That said, the two scores are not equally well evidenced: Jupiter Attack has 393 ratings behind it against 2, so its average is the more settled of the two. Written reviews complicate that: 40% of Jupiter Attack's written reviews are positive against 100% of Gem Tower Defense Mobile's, so the app with the better star average is not the one people write more warmly about.

UpkeepUpdate frequency

Jupiter Attack ships an update every 2 months, Gem Tower Defense Mobile weekly. Both last shipped on November 13, 2026.

Scorecard9 real differences · 2 level
Jupiter Attack versus Gem Tower Defense Mobile: the parameters behind the verdict, then further details
ParameterJupiter AttackGem Tower Defense Mobile
Price$1.99 — better$2.99
Rating4.5 (393 ratings) — better3.0 (2 ratings)
Positive reviews40.0% of reviews100.0% of reviews — better
Number of ratings393 — better2
Update frequencyEvery 2 monthsWeekly — better
AdsNoNo
In-app purchasesNoNo
MonetizationFree — betterPaid
Best chart rank#20 — better—
DevicesiPhone, iPad, iPod, Apple Watch — betteriPhone, iPad
Requires iOS12.1 — better26.0
Further details — not scored
Size18 MB12 MB
Age rating4+4+
DeveloperRed Sprite StudiosJameson DeVol

Customer experience

Jupiter Attack

All ratings383 ratings
Positive85.9%
Neutral7.8%
Negative6.3%
Written reviews10 reviews
Positive40.0%
Neutral10.0%
Negative50.0%

Gem Tower Defense Mobile

All ratings1 ratings
Positive100.0%
Neutral0.0%
Negative0.0%
Written reviews1 reviews
Positive100.0%
Neutral0.0%
Negative0.0%

In-app purchases

None

Jupiter Attack

No in-app purchases

None

Gem Tower Defense Mobile

No in-app purchases

Questions

Is Jupiter Attack free?
Jupiter Attack costs $1.99, with no in-app purchases.
Is Gem Tower Defense Mobile free?
Gem Tower Defense Mobile costs $2.99, with no in-app purchases.
Which has better reviews, Jupiter Attack or Gem Tower Defense Mobile?
Jupiter Attack is rated higher. Jupiter Attack averages 4.5 out of 5 from 393 ratings, while Gem Tower Defense Mobile averages 3.0 from 2 ratings.
Do Jupiter Attack or Gem Tower Defense Mobile have ads?
Neither Jupiter Attack nor Gem Tower Defense Mobile shows ads.
Which is updated more often, Jupiter Attack or Gem Tower Defense Mobile?
Jupiter Attack ships an update every 2 months, and Gem Tower Defense Mobile weekly. Most recently, Jupiter Attack was updated on November 13, 2026 and Gem Tower Defense Mobile on November 13, 2026.

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