Enigmata is a space shooter with tons of upgrades - Time Waster
As for gameplay itself, it's not that challenging if you repeat an easy level several times to collect gold and buff up your ship. However, learning to use special skills like bombs and shield recharging can also be important -- especially when facing some of the tougher end-of-level bosses.
Sometimes enemies drop X icons, which damage your ship, temporarily downgrade your firepower, or even steal your gold. These are avoidable, but they're the most annoying thing in the game. Fortunately, you can buy items that protect you from them as well.
Enigmata can seriously kill a few hours if you find yourself getting obsessed with having the best ship and unlocking all of the black market upgrades. Make sure you don't have any urgent appointments for the rest of the day before you start playing, because you might be there a while.
And god forbid you unlock the Legendary shop ... it contains a very expensive item that transports you to a level where the only enemies are bosses.