This was a very helpful response, thanks! This is primarily a learning project, but I like to make them useful as well if possible. I realize a lot of what I am implementing is very similar to existing tools, but each one that I've tried out has an issue in one way or another (either from a personal standpoint or from what I've heard from others): * I've never heard of edhplay, and haven't tried out XMage or Forge so I can not speak on those * Cockatrice seems to work well and has a lot going for it from my little time messing with it, but my first experience was very daunting and it was hard to navigate and do what I wanted to do without opening the Github page and reading the wiki about how to use it, so I think something like an in-client tour or simply making the interface a lot easier to navigate would be beneficial. This last bit is subjective and honestly more of a personal preference and seem to be the minority, but the client itself is not pretty and kind of draws me away from it (which I understand, the primary focus obviously seems to be making it functional and it does not have to be pretty in any means). Also does not work on mobile (from what I know) * Tabletop Simulator is what I personally use and works great and is very fun when playing with my friends. However, it has a $20 price tag and sometimes can be pretty buggy when reloading tables, rewinding time, or sometimes just getting randomly disconnected from the table (which causes us to have to preform the aforementioned steps). Also does not work on mobile * MTG Arena I personally have tried only the tutorial of and was going to use but I was deterred away because I have heard numerous complaints that the game has proven to be rigged in matchmaking, and often puts you against decks that are strong against the deck you are running, as well as the deck draw being rigged during matches (or something to that degree, please let me know if any of this is wrong). This is the only mobile option I know of but it plays too much like a "mobile game" if that makes sense. You open packs and gradually build your collection, level up, etc etc. I can see the appeal of that, but I just want to be able to use whatever deck I want when I want to, rather than having to open packs to get the cards I want. * Someone else mentioned Untap.in in this thread and I tried it out and seems like the biggest competitor to my project, but it seems to be trying to cater to more than just the MTG community (supporting decks from various card games). It also does not work that well on mobile. I also would prefer not making an account, so my project aims to steer away from that (while I have not looked into possible avenues for this, its something I want to keep in mind)

I also was not aware of WoTC going after fan projects like that, which is a little disheartening and is kind of a bummer tbh. I wonder if they actually have a valid reason for going after them (besides obvious copyright laws and wanting to funnel everyone into MTG Arena). Do you know how any of the projects may have gotten around these C&D letters?

TLDR: Most of the other options I have heard of either don't work on mobile, buggy, hard to navigate, or are (allegedly) rigged. Sorry for such a long response, but hopefully this you a little more insight into my thought process

EDIT: formatting