Robo Defense is the ultimate portable tower defense experience. Featuring open maps, upgradeable towers, stat upgrades, achievements, and nice graphics. The free version features 1 map with 11 difficulty levels.

Price: Free, $2.99

AndroidTapp.com Android Game Review:

Pros & Cons:

Pros

• Fun and challenging game
• Interchangeable weapons via sell back or upgrades
• Save game progress in paid version

Features:

Robo Defense Android App is your classic tower defense game yet adds monetary value to build your arsenal. The more waves of enemy combatants you eliminate, the more money you’re awarded to purchase artillery. The objective is to last as long as possible and gain as much money as possible completing levels.

I like this tower defense game the most of all others because the challenge level of enemies (some slow, fast, aerial, heavily armored, etc).

Hint: I find strategically positioning cannons to force enemies to run thru a maze to force a bottlenecks works.

Fun Factor & Addictive:

Robo Defense Android Game is addicting by nature, just when you think you’ve got a good defense going, the attacks will change up (best to be keep adding more and upgraded artillery in good positions).

Graphics:

The gaming graphics are decent, comparable to that of SNES.

Accelerometer, Vibration & Sound:

The game uses sound effects when shooting (an option you have to enable). 

Retro Defense is a tower defense game with a killer retro theme. Build your defenses to stop the invaders.

Price: Free, $4.99

AndroidTapp.com Android Game Review:

Features:

Retro Defense Android App is cool! A tower defense game with style. Retro Defense features 15 levels… each hours of play, 10 tower types, 6 invader types, 3 types of bonus tower, and Authentic retro sound FX.

Fun Factor & Addictive:

Although fun… it can be challenging as you progress to higher levels blasting enemy ships, which attributes to its addictive factor as you try to top your high score. That said, there is a level of strategy in tower placement and a bit of waiting in between arsenal attacks.

Graphics:

Retro Defense Android Game features awesome graphics sticking to its neon 80’s inspired retro theme. The developers website design is amazing too.

Accelerometer, Vibration & Sound:

Retro Defense Android Games uses sound and vibration (old school 80’s sounds… makes you feel like you’re back at the Arcade).