tank game on the Mattel Aquarius personal computer.
The Aquarius was Mattel's attempt to enter the burgeoning personal computer market, released in 1983. It's strange that Mattel would attempt to market a computer alongside the ECS or Entertainment Computer System that they also sold as an add-on to their Intellivision console, designed to turn the Master Component into a full-fledged computer. I guess it shows that the company had no real confidence in either system. At any rate, the Aquarius failed miserably as a home computer of the era. The writing was on the wall internally at Mattel; programmers had their own slogan for the machine, referring to its obsolete specifications by 1983 : "The System for the 70's".
For more information on Mattel Electronics and the Aquarius computer, consult your local Dot Eaters entry.