EDH cube - 99 + commander meant for 4 players drafting 6 packs of 20 cards. Each 2 color combination has a theme listed below and ~6-10 commanders available. Each 3 color combination has ~3 commanders available, approximately 1 matching each constituent 2 color combination.

Azorius: White/Blue - Blink
Boros: Red/White - Equipment
Dimir: Blue/Black - Steal
Golgari: Black/Green - Graveyard
Gruul: Red/Green - Lands
Izzet: Blue/Red - Spells/Card draw
Orzhov: White/Black - Life gain
Rakdos: Black/Red - Sacrifice
Selesnya: White/Green - Enchantments/Tokens
Simic: Blue/Green - Counters

Notes on tagging logic: For spells and enchantments, not all instants/sorceries/enchantments are tagged - only those that interact directly with the theme or are easy to cast to enable triggers (low CMC, or have mana reduction). Enchantment creatures are also tagged since they spot you a free trigger while serving other functions. All equipment are tagged. Good stuff means basically any deck in those colors wants to play it.

Some ongoing challenges - balancing red, lack of synergy for UB steal (most cards are just good stuff), a secondary tokens theme that doesn't go very deep (lots of good stuff is also tokens stuff), wanting to cut cube down to 960 cards for consistency, some fun but relatively weak cycles (dragons and ultimatums).