>>23423187
Engage GUNDAM is a what-if paper plan if Engage ZERO was chosen as the basis for the GP series instead of GP00.
The new animation project in UC Engage features it, but it's being tested in UC 0090 so as I understand Anaheim built it at a later date for data verification.
...that said it can still fit in the alternative version of events, or if we assume parts tested on it were used elsewhere instead.