Of that list, I'm definitely checking out Undetected [...]
Yeah, Undetected is really good; it services the "tactical espionage" part of its inspirator's tagline quite well. If you also like the original Metal Gear games, and if you haven't already, check out
UnMetal; it's top-notch. To make it clear to everyone that Metal Gear was the inspiration for the game, the developers even made a fake ad parodying the
"Gear Up." ad for Metal Gear for the NES. That alone tells you all you need to know about the game. It's a drolly coincidence that the names for both start with the same prefix, now that I think about it.
[...] I'm a huge fan of Mega Man Legends (I'd adore a collected set of those three games with some updated controls and such), so I'll give Halcyon Days a look for sure.
Don't forget about
Great Adventure on 5 Islands; it might be a mobile game, but it wasn't bad at all. Plus, it would be nice to have a game that, for all intents and purposes, has since been "lost" and therefore is long forgotten or wasn't even known about in the West.
While I'm at it, I might as well mention
Protodroid DeLTA, which began primarily as a Mega Man fan game that eventually became its very own thing, but it clearly pays homage to the series, particularly X and Legends; in fact, the developer is no stranger to the series given that he released a few fan projects based on them, both of which you can see
here and
here if interested. I haven't played it yet, but from all the footage I've seen, it looks good.
Also, I've no clue what's your preference toward fan-made games, but in regards to Mega Man Legends, there's one based around the third entry...or a recreation of what was shown before it was cancelled; it's called Mega Man Legends 3: The Prologue!. If you haven't checked it out already, it's in 8-bit, emulating the original NES games. To make things almost semi-official, the soundtrack was done by Makoto Tomozawa, which also received a limited physical release with original artwork by Hideki Ishikawa, both integral parts of the series. There's no landing page for the game, but
here's the official preview video, and if you, or anybody else who's reading this, happens to be interested, a link to download the game can be
found here. Just follow the prompts on each screen, and when you reach the last page, input "dash3" in the field when asked for the password (without the quotation marks, of course). It's a fun game.
Anyway, to keep the topic going, here's another one:
Devil Spire. I fortuitously came upon it and had to share it, although it's from 2022, so I honestly have no clue how I didn't find it sooner—maybe you did?
Plastomorphosis was also released last month, too; it looks cool.
And last but not least,
Slave Zero X, which is a prequel to Slave Zero that was released digitally last week; it's basically a PS1 title released nearly three decades later, and I'm all in for it. The people behind it are quite inattentive, though, given that I emailed them nearly two months ago regarding the physical release of the game, specifically the Calamity Edition, and I've yet to receive a reply from them, not even an automated one.
And that'd be it. Enjoy.