I'd never heard of them, but after checking out some of their songs they are clearly hard trance + commercial dance music ("euro trance" too if you want to add that). They really don't have one specific style, but instead blend multiple genres together.
The Prodigy are firmly "big beat" along with Fatboy Slim and the Chemical Brothers.
Euro trance is a weird subgenre. Normally you would think that it's just trance with eurodance-y elements, but a lot of those tracks also fall within the other flavors of uplifting (ex. epic trance, Dutch trance, anthem trance, uplifting trance, each with their own quirks). Of course, once you start getting
really into it you're back in the late '90s/early 2000s when people wanted to assign specific subgenres to everything.
If we go by
Ishkur's old guide to electronic music, Out of the Blue is firmly Dutch trance (along with Rank 1 - Airwave), and Sandstorm is anthem trance (which is the same subgenre as Transa). Then again, Ishkur considers Castles in the Sky and Better Off Alone as epic trance, which is the same subgenre as For an Angel and Synaesthesia, so...
¯\_(ツ)_/¯