For Xerons, read Galaxians. Apart from being a good implementation of a well-known theme, the matrix of colour, form and movement all lead to impressive screen displays.
Each time a galactic formation is annihilated, a more complex armada replaces it, increasing the visual impact. Every stage is colour-coded; the early ones are fairly easy but not too many players will storm through latter screens.
The enemy ships come in three styles (my favourite being the multi-colour variants). All whirl, dive, drop bombs and generally convolute into the most awkward situations. A hit on the lone stalwart laser base generates a retina-rasping routine with the possible odd curse from the controller. The explosions sound good and beefy, indicating something solid has been hit.
The best advice I can give is to compare it with Anirog's Galaxy, then decide which is for you.