Alien Breed is an isometric sci-fi shooter where you independently control the direction your character aims and moves. You maneuver through a series of 5 stages in each episode, collecting weapons and items, and shooting aliens as they appear while you move from objective to objective provided on your mini-map.
It is difficult to write a separate review for each Episode, as they all largely play the same - you move from point A to point B to pick up access code C to open door D to get to point E to get access code F to.....you get the picture. Lots of backtracking through same-looking corridors, fighting similar looking enemies which pop out of the floor and walls.
It's fun, but only moderately so - I would NOT recommend playing through a single episode in one sitting, let alone all three episodes. The gameplay is repetitive and it's the sort of thing you'll want to put down for a while between sessions (I'd actually say on the level of months between episodes) so it doesn't get stale.
I will note that the third episode is easily the most difficult of the three, so if you're looking for a challenge, this one is probably the one to look at.