So there's a PC fan sequel to the Gungriffon Saturn games, that looks pretty rad and faithful (maybe too faithful, I could do without the Saturn draw distance, ha).
HIGH-MACS simulator official page
grape65535.jp
I'm definitely giving it a shot at some point, some random guy in the Project Wingman discord spoke about it after I started babbling about old school faux sims.
I tried this for a little bit and it's great. The gameplay being mouse and keyboard based given the platform is more like standard modern FPS controls but with the mech arsenal and movement capabilities so it feels a bit more conventional than the Saturn games (I’ll have to see if any controls can be mapped to a flight stick or something but I doubt it, plus it’s so hard you might need all the speed and precision the mouse affords). Other than that it seems super faithful and well made with the way the missions work, your various hud elements, weapons systems and everything else. So, the surrounding Gungriffon elements are all there but the core gameplay is more modern and advanced so it’s not exactly like playing the Saturn games, they should be judged/enjoyed separately. It also doesn’t appear to have training levels or anything super easy to get started with so it’s just fast and chaotic from the get go and might seem frustrating before getting the basics (ie don’t try to use your normal cannon to shoot down planes zipping by, either some spread machinegun fire or homing missiles are your best bet). Also every element has been expanded in some way so it really does feel like a sequel. There’s no way the Saturn could do all this even if the graphics are still low fi in all the right ways but it would be amazing on the Dreamcast (and look better, closer to Rise from the Ashes but not quite given the scale/action).
Update: you CAN actually map a dinput flight stick (or any such gamepad I guess, I don't know about xinput, it seems to only work with the first device it grabs, you may need to unplug others to map the one you want, but my flight stick was first anyway) and also select between different schemes, modern or traditional. I’ve almost got it very similar to my MechWarrior 4: Mercenaries control scheme but I’m having some trouble, the moment I use “turret turn” my “turn” axis also becomes turret turn and both axis have the same exact result until the turret reaches its max 45 degree angle at which point both axis just turn the mech in that direction (or turret turn in the other), even though before doing any turret turning simply turning works as it should with the turret centered. I don’t get it, maybe it’s bugged and I’ll simply have to play with the mouse and keyboard (which is fine) or I don’t quite understand the configuration and menus yet. There is a training tutorial (but I can’t progress before figuring out what it asks, it resets if you do something else) after all and the survival mode from Gungriffon II.