The story mode is split into 5 chapters which see Conrad navigate through the corridors and rooms of a spaceship, eliminating any aliens that stand in his way. The story isn't well developed, but all you need to know is that your ship is in a bad state and has been boarded by aliens.
Initially armed with a basic pistol with unlimited ammunition, Conrad moves around the ship, guided by way-points marked on your map. The frequency of way-points mean you can never get lost and therefore concentrate on shooting. If you do notice open doors, you can venture off track in order to find extra pick-ups. These include ammunition, grenades, health packs and credits. Credits can be spent on a few upgrades or purchase extra ammunition from the terminals where you save your progress.
Conrad is usually given an objective to interact with the ships mechanisms but it's never that simple given the ships state. So then you have to take a detour and complete sub-objectives instead, or an alternate plan is given. For example, you may be given an objective to restart a generator, but it fails to start, so then you need to power-up the back-up system instead. As far as you're concerned, you just follow the new way-points and shoot anything in your path.
As Conrad moves around the corridors, there's plenty of explosions which is a nice visual effect which illustrates the ship's poor state. However, it's far too overdone and gets a bit ridiculous how everything seems to explode when you are in close proximity. There's also plenty of aliens popping up through the floor, or bursting through the walls to try and ambush you. Although it's not a scary game per-se, the aliens charging in suddenly could be considered a jump-scare at times.
As you progress through the game, you are given new guns which include shotgun, assault rifle, flame-thrower, and laser rifle. These weapons have limited ammunition, so you have to use them a bit sparingly. On the plus side, they are far more powerful than the basic pistol. The general strategy is to try and conserve ammunition when there's little threat, especially when you encounter the smaller aliens that can be taken down with one pistol shot. When the threat is greater, you switch to the big guns to quickly eradicate the horde.
I opted for the default controls which is using WASD to move, and the mouse to aim. Left-click shoots, right-click uses secondary equipment like health packs and grenades. R is used to reload, Z/X scrolls through the secondary equipment, mouse-wheel scrolls through guns. Q/E quickly pans the camera, or you can do the mouse to do so. You can run with Shift but Conrad cannot aim whilst running and fatigues with continued use; so is only used in short bursts. Ctrl gives a mêlée attack if the aliens are in close proximity.
The lack of game-play variety may be a concern to some, but Alien Breed provides a fun shooter at around 5 hours of game time. Although the end boss is disappointing, the game seems to last about the right length given the game-play. The game is part of a trilogy, so this is only really a third of the game. If the other games are more of the same, it could easily become monotonous by the final installment, but due to the weak story, you can enjoy the game in isolation.