The variations in unlockable game modes and ship customization allow for some fun replays and twists. It's fast paced, has some quirky humour, does not take itself too seriously and the music and sound effects are very good for this type of game to blaze through.
I wouldn't compare it too much with Raptor, which feels a little slower and more serious in tone and structure, Tyrian is lighter and faster, it has less economy grind than Raptor but you just start over again after finishing the campaigns and unlocking the next mode. More often than not, it will stop needing digital currency and you can just collect what you need on the map in arcade style modes, allowing for even more continuous play with less interruptions.
It also comes with a complete minigame that you can do in multiplayer (meaning: share your keyboard) or vs the computer if you find the final secret code ;-)
There are exceptionally few dislikes I can find for this gem.