Omega Crisis is played with a combination of mouse and keyboard; point and click to shoot your cannon, and use the keyboard controls to pan around the area and locate incoming enemies. A warning siren will go off whenever enemy ships are about to appear, indicated on the map. It's in your best interests to shoot down enemies before they get close, not only so you don't, y'know, die, but also to earn tech points you can spend on upgrades between levels. (If you want, you can also replay levels you've already won to earn even more points.) You'll also earn resources that you can use to build more defenses by shifting into management mode; tap the [spacebar] to bring up a grid you can build on. You can only place a certain number of defenses, as limited by your power supply, so think carefully about what each stage throws at you to get the most out of your resources.
Keep an eye on your base's health bar, and on the timer in the bottom left that counts down to each new enemy attack. The further you go, the stronger your enemies get, but you'll gain access to stronger weapons and even gain a warship to help along the way. Although your base heals all damage between levels, your defenses do not carry over from level to level. This, I believe, is best described as SHENANIGANS syndrome.
Analysis: Lucidrine is rapidly becoming known for space-faring, high action adventures, so this slower paced defense/resource management hybrid was a bit of a surprise after the frantic intensity of, say, Cube Colossus. Omega Crisis is still very polished, but the comparatively slower gameplay makes it feel a bit restrained; more tense than adrenaline fueled excitement as you watch enemies swarm towards you and your defenses struggle to keep up.
Early on, the game is exceptionally easy if you find and park yourself over the enemy's entry point as soon as you hear the warning siren; this lets you simply lay down a continuous stream of fire that obliterates them the moment they emerge. As stronger enemies begin to arrive, however, and from multiple directions at once, juggling them all becomes a bit of a challenge that forces you to think strategically about using your defenses. Some stages also make an effort to increase the challenge by disabling your main cannon, forcing you to rely on carefully placing your defense systems instead. The downside is that enemy AI is still extremely limited, and ships tend to just fly straight towards you making no effort to avoid fire. The game makes some effort to explain this, but I'd still expect something more from an advanced civilization.
At only ten stages, Omega Crisis is more of an appetizer than a full meal; even if you replay stages to earn more upgrade points, you're probably only looking at a few hours of play rather than a full starfleet career. Despite a few bumps in its design, and the lack of any real story to speak of to drive you forward, it remains a fun challenge to sink your teeth into, if only for a while.