Avalon Hill was once known as a maker of those kinds of games that made even Dungeons and Dragons fans wince -- lots of hexagonal mapping, stats kept on notepads, and the kind of calm, reasoned long-term planning that video gaming was supposed to beat out of us, not encourage. While they made a number of forays into the 80's computer market, their only two TI 99/4A offerings (to my knowledge) were B-1 Nuclear Bomber and this little-known strategy head-scratcher, Galaxy.
Any game that comes with its own score pad would have probably sent me running for the door in 1983. Even now, it rankles a little bit -- wasn't keeping track of stats and figures why we involved the computer in the game to begin with? But get over that, because Galaxy is all the richer for making you keep track of your own expeditions and upcoming battles.
Briefly, Galaxy generates a (wait for it...) galaxy of an adjustable number of planets. Each one has a poor-to-fair capacity for manufacturing spaceships. You occupy a home world and command a fleet of these warbirds, and your goal is conquest of the rest of that map -- the whole thing, in the allotted time, if you're playing alone, or just more than your opponent(s) if more than one human is involved.
The distance between planets determines how many turns (months) it will take your fleet to arrive at the planet you wish to attack. Also, you have no way of knowing -- until your forces arrive -- whether this planet has any industrial capacity, or is defended at all. On top of all that, it's up to you to keep track of what fleets you've sent out into the ether -- say you launched 20 ships from your home planet, Planet A, to faraway Planet Q. Once you've sent them, there's no marker on the screen to gauge their progress, no way to communicate with them or call them back... they're out of your control, and might as well have disappeared, until they arrive at their destination.