The bogies warp in near your ship in waves and follow fixed paths around the ship scouting for prey.

If you learn the patterns of waves and paths you can pick off the bogies with ease while they are scouting. It won't get you high scores, but you can speedrun the levels that way.

The faster you are travelling when you fire a shot, the more points you earn if the shot hits a bogey. But be careful. On higher levels, you can collide with the ship's superstructure. While your pod is pretty robust and bounces off at low speeds, at high speed collisions damage your pod.

Collisions with bogeys also damage your pod. You don't get any points for colliding with bogeys.

The "turret lock" lets you strafe the bogeys at high speed with less chance of collision.

If a bogey reaches the end of its path, it starts hunting the crew. It's body flashes between yellow and green, and it moves faster. You earn more points for taking out a bogey when it is hunting than when it is scouting.

When a bogey reaches the crew member it is hunting, it abducts the crew member. It then flies away from the player. It moves quite slowly when carrying an abducted crew member. Bogey's carrying an abducted crew member are highlighted as red blips on your pod's radar.

You can free the crew by shooting the bogey. Your shot propels the crew member in the same direction. Shoot from the right angle, and your shot will propel them back onto the deck of the ship.

If you shoot them in the wrong direction, they will float off into space to their doom.

Your only hope then is that another bogey will abduct them before they run out of air.

They can only land on the deck of the ship, not on the machinery and piping.

When a crew member lands on the deck, you get bonus points. The further they travel, the more points you get. One method to earn high scores is to let aliens carry your crew members far from the ship before freeing them. But leaving it too long is risky -- it's harder to direct the astronaut back to the ship, the alien might merge with the human before you shoot it and mutate into a more dangerous form, the freed crew member might run out of air before reaching the ship, or another alien might abduct the freed crew member again while they are floating in space. And in the meantime, other aliens are attacking the crew members still on the ship.

You've got to walk a tightrope between risk and reward to earn top scores without the whole situation collapsing into chaos.