Quick Play/"Roguelike" Mode
(obviously not an immediate need but could be a fun side-mode much later on).
A mode that gives you a random smattering of tier-appropriate synapses/gear/mind tree points, gives you a chance to build a loadout, and throws you into an extended Mind Dungeon that gets harder as you go (higher instability cap, deeper depth, new patient modifiers). Transposition loot rewards now provides things like healing, Awareness, and room clear buffs.
A mode like this would limit one's build choices and ignore long-term-rewards, and thus encourage improvisation and difficult tactical play.