Piano Forum

I don't think it's even considered contentious, he's definitely a Romantic composer.  It's far less harmonically/melodically explorative than Mahler or Strauss, for example, but they're certainly considered Romantic.

Scriabin's later works are usually described as "Futurist" rather than Romantic (e.g. Sonatas 5-10, Vers la flamme, Etudes Op. 65).  It's much easier to just hear what differentiates "Futurism" in music than try to describe its technical differences from Romantic or this-or-that "modern/contemporary" style:

Futurism uses a lot of the figurative aspects in terms of both writing and performance from the Romantic composers, and also uses classical notions of key modulation, but does not use classical harmony.  Instead, they use a notion similar to a 'pitch center' but instead it's a 'chord center(s)'; or, you can think of it as using alternative scale systems.  Often they're dissonant and usually incorporate (or nearly incorporate) the Mystic Chord.  But instead of some other alternative scale system (like the pentatonic on the black keys), they'll modulate that pitch center around just like how classical harmony will have key changes (so moving off the black keys to other pentatonic scales).  Scriabin in particular often likes to use mode changes within his pseudo-scales as well, especially in the Op. 65 and Op. 67.  In these alternative scale systems these modulations don't always have the same 'musical meaning' as they would normally, but often they will be similar enough and the composers would exploit that to build narrative.