The C-64 version, uniquely I believe, had the ‘Trumble’ mission too. Basically you’d be offered an exotic pet when you reached 6553.5 credits. This pet would sit in your cargo hold and then consume anything edible, eventually infesting your forward screen. The only way to get rid of them was to fly close to the sun and kill them off through excessive heat. They were clearly a nod to StarTrek’s Tribbles, but they were reputedly named after Donald and Douglas Trumbull, father and son pioneer team of many motion picture special effects.