I think polymorph-type effects would be a great design space to explore. Fireflux Squad & Reality Scramble are underappreciated

There are some ways you can explore to overcome some control strategies, some of them are not what you typically think they are. I've played a TON of games beating very different levels of competition with deck themes that are generally not thought of as the most "winningest strategy" or having the most "staples"

My Atla damage deck has killed many a player in response to their lame cyclonic rifts for example & it does so without a single combo (no combo Atla here) & it does so without a single tutor.

Breena walkers has out-grinded & punched many-a-mouth & almost no one thinks planeswalkers is going to be a huge problem.

Pen-&-Paper RPG would have some of what you are looking for. DnD is cooperative, highly social. Arkham Horror would be a coop board-game, though that would be old pulp-fiction Horror-based. Though those things are usually even "weirder" if you have a sortof straight-&-narrow family. I've found DnD has been taking over alot of my playgroup's timeslots together... Probably because upkeep costs ($$) are so much lower & are more able to enjoy snacks & good booze with DnD than we usually get to with MtG.

Power creep & tempo creep are definitely things to look out for in MtG, it is the same reason I keep seeing more all-or-nothing builds where you are talking about a minimal land-base with tons of fast mana.... & absolutely Zero panache to the decks. PERSONALLY, I have been much more into groupslug decks & when you find a playgroup with more sluggers in it you find some really FUN games of magic. It is a bizarre thing where the average meta are trying to accomplish the same goal... controlly wins for example, but as soon as you shift to the meta playing for a race to: "death by 1,000 cuts" you actually find that the average -splash deck is woefully pushed out of that type of game.

I am surprised that you would receive less $$ than you invested in the game though. I have made a bundle of $$ just selling off chunks of my collection to a major vendor (I think I am not supposed to namedrop them on here?). Maybe I just predicted some stuff that I bought low on though. I only ever buy low on singles... So I had like 8x field of the dead for example, because I had a feeling about it

On the low-CMC end, Collector's Vault has really put in some sneaky-good work for me. Building my GY, filtering cards, & ramping for next turn.

Speaking of underappreciated gem(s); Breach the Multiverse really puts me right back into/closes out games like crazy.. I have yet to have that card not make a huge impact yet.