Imagic threw the best features of two successful arcade games together and came up with Nova Blast, a hybrid video game for the Intellivision system.

From Defender it took the screen scrolling from side to side and a radar screen. From Missile Command came the cities which need protecting from an onslaught of aliens.

Sounds good - but unfortunately the two elements have not knitted into a well-balanced game.

Your craft shoots along above an ocean, with four cities lying, like Atlantis, beneath the waves. These are protected by energy barriers from the alien hordes which dive out of the skies.

But one direct hit is enough to destroy the barrier and the next hit will destroy the city itself.

Barriers can be replenished by your aircraft by use of a beam. You slow down over a energy source to beam it onboard and them beam it down to your undefended city.

Of course energy sources tend to be some way from the cities, so you have to leave a city unguarded to collect new supplies.

Radar shows whether a city has its barriers up or down and it also shows your craft and the aliens.

The aliens are rather unimaginative in design and hurl themselves around the screen only slowing down over the city target and going into a spiralling dive onto the cities - they don't miss.

Water walkers are the underwater peril as they stalk your cities they hurl bombs skywars. Aliens come in waves and bonus scores are built up for each city still standing after each wave.

On the easy levels, the trick for saving at least one city is soon learnt. On other levels, thought is needed to combat the walkers.

Graphically disappointing, Nova Blast suffers from the predictability of alien movement; they just overwhelm your cities by a sheer force of numbers!

Guilty of unimaginative game design which relies too much on old ideas which worked well in other games, but not in Nova Blast.