1) There's some good stuff there in the Microsoft Store, but you have to look sharp and be on your toes. There is a lot of crapware, but there's a few good apps, too. A good place to start on validating is checking who the publisher is, and checking the links for the app's website and privacy policy, and checking app permissions (though, security settings can override some of those). And if you're still in doubt, like in the case of the version of VLC on the Microsoft Store, get the link from the developer's website directly. If there's no link to the app version in the store from the official website, that's a clue that something unsavory is up with the version you found.
Some personal favorites from the store includes: Microsoft's Diagnostic Data Viewer, f.lux, Libby, MyRadar, myTube!, NotepadX, PAWA, QR Scanner+, Microsoft Translator, vxUtil, and WiFi Analyzer.
Alternatively...
PortableApps is a good alternative for some simpler applications/utilities that are mostly self-contained and don't actually install to the system and community curated, which means you can lock the system down further and still use some apps without having to actually install them to the system. There's also
Ninite installer, which downloads directly from the publishers and simplifies installing and updating a lot of useful apps, and auto-bypasses installing any optional crap like toolbars.
2) Defender is okay, and I used to run it exclusively for a few years, but the past year or so I've started using either
Avira (
does not require online account for registration) or
Bitdefender's (requires online account for registration) free AV solutions as the primary AV scanner these days as Defender's quality has been a bit off its game lately. This said, normally don't just randomly download apps off of random websites, but try to download directly when possible from the official website. If that's not an option,
LO4D will typically have clean downloads, but visit with an adblocker and pay attention to
where you click for downloading, and I'll usually re-check on my own anyway. For checking
any downloads with basically every single available antivirus utility, use
VirusTotal. Most mainstream download sites
have gotten ugly, though. Try not to download any apps to install from anywhere but the official website from trusted developers, though,
seriously.3a) Good news!
WinAero has the old Windows 7 default packaged game apps available for download and install under Windows 10, and it includes the venerable Chess Titans in addition to Solitaire, Minesweeper, and the like. I know the download is safe,
but practice best practices anyway and check the download with VirusTotal. Just be careful during install and read every installer window prompt to make sure you don't accidentally install the WinAero Tweaker there at the end. The only downside is that you'll have to reinstall the games after every
major Win10 service pack upgrade (like, once a year), so you might as well keep the installer handy.
PortableApps also has
LucasChess available in their software library.
3b) Desktop widgets can potentially open up additional vectors compromising system security (why Microsoft dropped them), but
Rainmeter's okay-ish, and there's more than a few analog clocks and calendar themes available among a whole slew other things... but again, scan
everything and understand the risks of running this stuff.
3c)
Archive.org has several versions of the real thing from several platforms (Atari, DOS, Gamegear, NES, etc., among other platforms intermixed with many other games) available to play in browser, all legal like.
Here's the DOS version which seems to work really well. Archive.org's
Wayback Machine is also very useful for finding obscure software titles or apps from an official website that a publisher no longer offers. I don't know much about the Windows native clones out there.
3d)
XnView has RAW image file support as well as
a slideshow viewer that allows for either timed or manual image advancement.
Enjoy.