The premise of the game is very similar to other tower defense games. You place different towers around each level and then stream enemies through them, attempting to destroy them before they get to your base. In Radiant Defense, you have to protect a portal from aliens trying to invade Earth.
Visuals in Radiant Defense have a neon light effect on all the towers and enemies. It creates a stark difference between the background and the animation on screen. Watching Radiant Defense in motion is a lot of fun because of the large amount of action that can happen on screen.
Gameplay in Radiant Defense is really not different from most tower defense games, but it does allow you to set your own paths by placing modules around the level creating longer paths for the enemies to fly through. Add in different weapons like lasers and tesla coils, and there is a definite science fiction feel.
Radiant Defense is a lot of fun to play, because the game is challenging and can become very addictive quickly.