Same Rules, Same Setting, Multiple Scales?

[Cat]

Umm, guilty on multiple counts.
 
Blitzkrieg Commander in 1/87; and the club was playing in 1/285, so I added a small force to bring along for that.

Homebrew rules for Girls und Panzer in 1/100; and since we're working on a home Japanese model railroad, also picked up 1/144 tanks to  play on the layout.
 
[Also Bolt action in 28mm, so WW2 in general in 5 scales].

Battletech Alpha Strike in 1/285 and 1/144.

DBA mostly in 15mm, but also 6mm and 25mm (with overlapping armies between scales).

[Daeothar]

Not exactly what the OP means, but gaming with Dropzone Commander (1:150) and Dropfleet Commander (1:15K), we have always had the intention of combining both games into a campaign, where there'll be fleet actions first, dropping troops on planet with DFC. After which we'd switch to DZC to play out the ground conflict.

I'd always expected Hawk Wargames to eventually come out with a 28/30mm Dropsquad Commander game as well to zoom in even more, into skirmish territory, but that never happened, but if it had, we would probably have added this to the campaign plans too.

But as to playing the same rules with differently scaled miniatures though; I'm going to have to say no. the closest I've come is to simply replace the 15mm miniatures of Team Yankee with 1:300 ones, so that the ranges are a bit more realistic. But that never actually happened...

[eilif]

I've managed to keep nearly everything in 28mm'ish.
However, I play Mech Attack in 10mm and 28mm.   The club started playing it about 10 years ago when Mech Warrior Dark Age minis were cheap as chips and being sold by the bucket so we were able to simply rebase them (though some repainted) and do some affordable mech gaming without redirecting much time or cash from our regular focus on 28mm.  We ended up using those minis in a few other small scale games, but not the same games as we were playing in 28mm.

However, we eventually started running a yearly Mech Attack game in 28mm using a variety of Mech miniatures, models and toys.  Same exact ruleset, just doubled ranges.  I only put the game on once or twice a year, but it's an incredible setup and folks really enjoy it so it's worth it to me. https://www.chicagoskirmishwargames.com/blog/2022/04/aar-mech-attack-battle-at-adepticon-2022/

Right now I'm kicking around the idea of making a convention game that would use 1/18 (3.75) action figures as the miniatures.  Perhaps using something like Planet 28, a ruleset my son and I want to try in 28mm.

In regards to Dragon Rampant, second-hand (often off-brand) 25/28mm figures are so cheap that -unless you have a group of 20mm fans- I think worth it to build in 25/28 if only to increase the number of opponents you can find and the number of other miniatures-agnostic rulesets you can use them with. Club members discussed a few times doing large fantasy battles in 15mm and 10mm, but in the end we just kept growing our mostly-bargain-sourced 28mm armies and played games of Dragon Rampant until we were able to field armies for KoW.