Links: Browser Based Games
Well, mostly. Due to the death of flash, some of these are now downloads. But, I think it's the spirit of it that counts.
I'll have a description for each game written so you can get a sense of what is required or how accessible it is.
In no particular order...
Before You Play...
Ruffle
A reliable Flash Player emulator. I have used this to play Neopets flash games, mostly, but it really does a lot. You can download it as a browser extension and I strongly recommend doing so if you are really into these types of games. Important to note that sometimes having Ruffle installed can play some broken materials on the Wayback Machine as well (although, I've only had this success once).
Flashpoint Archive
It's a software package but also an archive. The community is very active so I recommend getting involved if this is something you care about or if you happen to have some files to donate.
Pale Moon Browser
Certain games function better in this browser than in Chrome. Not really nessecary though with the popularity of Ruffle.
Games: General
Pokemon Showdown
Works in browser.
Pokemon Showdown is so great it can provide you with infinite fun. You can play random battles, with friends... I often use it to test teams I want to run in my different save files.
Flowergame.net
Works in browser and on mobile devices.
A very relaxing, charming game where you collect flowers and care for them until they grow. Then you get to plant them in your garden : )
Pokefarm Q
Works in browser and on mobile devices.
A clicker game where you collect and raise Pokemon by giving and receiving clicks from other users. Has very cool features, like Albino Pokemon which are rarer than Shiny Pokemon, and Melanistic Pokemon, where a Pokemon is both Albino and Shiny at the same time. It's a thrill to hunt for these Pokemon.
Pokeheroes
Works in browser and on mobile devices.
Adopt and hatch Pokemon, works similarly to Pokefarm Q from what I understand. I have yet to play this one, but it looks very nice.
MahjongSoul
Works in browser but you can also download an app if you prefer.
Riichi Mahjong... cute anime girls... guys I don't know what to tell you it is very easy to get hooked on this and have it be the start of your day alongside a nice cup of coffee. I love women.
The Asenheim Project
Works in browser and on mobile devices.
A retro visual novel player and database. Some very cool stuff here and it is a novelty to play these games on the go or on the bus. Just uh... tilt your phone away from people for certain... scenes.
Pokeclicker
Works in browser and on mobile devices.
Like cookie clicker but Pokemon. You click a lot to progress. Has a dungeon crawling feature. You can hunt shiny Pokemon as well. It's very mindless and pretty enjoyable if that is what you are looking for. New features are being added often. The site recommends installing it and you get exclusive benefits from doing so, so it's worth noting.
FairyABC (Pixie Hollow Rewritten)
Works on PC.
I haven't played this one yet but the site aims to revive the popular (defunct) online game, Disney's Pixie Hollow.
Everskies
Works on PC and mobile devices (as an app).
I have not played this yet. A doll dress-up game. There is a big emphasis on the social element of the game which can be a very mixed bag. The fashion is really fun though.
Gaia Online
Works on PC and mobile devices.
The OG!!! Still so cute and charming even though the economy is totally busted. LOL. I hope one day I can get really good at this site but until then my account collects dust.
Newgrounds
Works on PC (idk about mobile I have not tried).
I love the gems that are still on here after all this time.
Pet Collecting/Management Games
Neopets
This can run on mobile, ipad and computers.
While I absolutely despise the mobile site design, Neopets is capable of being played on basically everything. And trust me, I have. Very active, like you would not believe how seriously people take the game. Also, Neopets just got new management so it looks like there are more things to come from the brand (flash games and many bugs have been finally fixed that have been wasting away for years).
If you are interested in playing or have never played a pet game before, there is a learning curve. Check out my Neopets links to find countless resources. I will add you as a Neofriend if you ask : )
Flight Rising
This can run on mobile, ipad and computers.
You collect dragons and they have baby dragons which you can try to make certain colors... people take it very seriously. The site launches events and does a lot of fun things for their fanbase. Very rewarding game without the hiccups of a lot of other browser based games... I just couldn't really get into it, I dunno why : (
Goatlings
This can run on mobile, ipad and computers.
You take care of cute little goats. It's very sweet to look at and seems to be newbie friendly. I don't have much personal experience with this one.
Marapets
This can run on mobile, ipad and computers.
Marapets is a lot like Neopets but it takes new features and runs with it. This is both it's strength and it's weakness.
ramblings
It feels very alien and disjointed in many places but at the same time, features like school items actually having a purpose is a novelty I really enjoy. I like making my pets numbers go up. Be warned, the staff of Marapets is... very strange? Ian (the admin) has a lot of attitude and is extremely unprofessional/rude. There's a big problem with the way the game baits you into paying real money because you can purchase limited pets (Neopets on the other hand just baits you into buying wearables, so no real consequence). Also, it might not bother people but there is an extremely uncomfortable amount of demonic imagery and humor. I found it kind of startling and it ultimately made me stop playing because it did not have a warm cozy feeling. To me. I did sink a lot of time into my account though. LOL.
Lioden
This can run on mobile, ipad and computers.
Feels sort of like Flight Rising but the focus is on lions. It's really cute, I haven't gotten very into it yet though : )
ChickenSmoothie
This can run on mobile, ipad and computers.
Adopt pets once a month or at special events (like mass adopt pets is the name of the game... you will have hundreds). You can trade with other users, dress up your pets. There's an oekaki board on the site. Most of the gameplay features come from events (which there are a lot of) or from participating in the forums.
Download Required Games
Adventure Quest
Requires a download of the Artix Game Launcher. Exactly how I remember it, even today. It has that pseudo-anime style that is oh-so-charming. VERY slow to play... takes a certain kind of person to appreciate it. If you've never heard of it, I recommend checking it out just for the novelty. Listen to Linkin Park while you play it for the optimum expierence.
Webkinz Classic
Requires a download of Webkinz Game Launcher. I still really enjoy Webkinz and I'm really glad they are keeping support for classic while they launch the modern version.
Old School Runescape
Requires a download of the Jagex Launcher. I just love that you can still play this thing. Unsure of the state of things but it seems to be trucking along healthily and it should continue to recieve support for the foreseeable future : )
MoshiMonsters Rewritten
Requires a download of the MMR Desktop Launcher.
I have yet to play this but I also never played MoshiMonsters retail. Seems interesting though!
Direct Neopets Clones (And What Makes Them Different)
Neopets Classic
my personal review
Keeps the old OLD layout that we all fondly remember. Neopets Classic, to me, felt like the most put together of the Neopets clones I have played BUT that was before some fandom drama went down.
Joining the discord is basically nessecary (annoying), there's drama or whatever with the community vs the team, there used to be a dailies site that was like JellyNeo but I can't find it now. And after logging into my account after a long time (wiping off the dust) I can't find the dailies tab easily and the browser extensions I had no longer work. I feel like this game would be extremely difficult to play if you aren't a Neopets veteran because, unlike Neopets, there isn't a very large userbase so it can take a while to find items you are looking for, to have people buy your items, etc. That being said, you can use tokens to have (basically) as many pets as you like, and the prices of most things are very, very low as there is nowhere near as big of a demand for them. I had the most fun getting avatars that are (basically) impossible to obtain on Retail Neo.
Modern Neopets
my personal review
Keeps the old layout as well. However, it is easy to find your dailies on board the site which is a HUGE plus. Has more fan-made colors and pets, which can be a plus or a negative depending on your point of view. The organization style makes this easily the best option of all the clones. Also, haven't heard tell of much unnessecary drama, although I am sure there is some as there always is with Discord servers. Joining the discord is basically mandatory, again (annoying). It feels kind of like Toyhou.se so take that as you will. I'm pretty sure you need to pay to get an account invite code or you can wait until monthly signups. Same economy issues (and bonuses?) as NeoClassic. As of time of writing, 89 players were online which is a pretty high number for this type of game, all things considered.
Leopets
my personal review
Way more custom/creative pets that stray from retail Neopets. You gain entry by completeing an application at the beginning of the month. I've never gotten my application approved even though I've applied a number of times... LOL. From what I can tell, this community is very small and very tight knit. I'm not entirely sure if it is even really active or not?
A note on Neopets Clones: These websites continue to crop up so I will post the ones that I test out here. Important to note that these websites are usually destroyed by their own social issues. Investing time into them and getting emotionally attached is somewhat dangerous as realistically, it could be taken down at any time. So don't take them too seriously : )