Can someone recommend some albums--game soundtracks or otherwise--with a style similar to the rousing and thunderous music of the Ace Combat series? I'm looking for something to suffice until the Ace Combat 6 soundtrack is released.
As much as you might be referring to specific entries by "rousing and thunderous", I think the music of ACE COMBAT series varies way too much to talk about as only a certain style of music. This is mainly because there are many composers who have worked on this series so far, and some of them are no longer involved anymore. Roughly speaking, 1 and 2 are lighter rock and have a decent fanbase. However, after Kohta Takahashi who I think was the main composer of these games gave in his resignation to Namco as soon as the development of 2 was finished, good AC rock was dead. Then, AC3 became a pretty electronic album, mainly because the game got more based on the sci-fi setting.
From 4, all that said, we can probably describe all of the subsequent AC music by a few word. Although I'd consider myself as an avid fan of Keiki Kobayashi and I admit to almost crying every time I watch AC6 footage, to me, much of the scores for 4, 5 and ZERO are basically lifeless orchestra music which I think is not so hard to find in today's VGM industry, with some rock, electronic, or even quasi-flamenco elements. ACX is a blend of orchestra and electronica (IIRC, the staff credit theme is jazz), but they are composed by external composers. Air Combat 22? I don't know...
As far as Kobayashi and Nakatsuru go, though, of what I've heard, Soul Calibur III has a certain similarity to ACE COMBAT because both of them work on this game too (SC is much more colorful, partly due to its wider usage of woodwinds and many other instruments, though). With regard to Nakanishi and Okubo... well, I hope some RR fanboys/girls tell you something.
Btw, if you are exclusively referring to those final level themes, that's exactly what I'd also love to know. I once suspected Kobayashi had been inspired by Verdi's Requiem "Dies Irae" when composing "ZERO" (and as we know, the lyric of "Megalith" is from its " Agnus Dei").