Okay, we already have the tier stars in the character progress tab - I'd like that data to also fill in a gate passport booklet:
gate passport book has all gate emblems possible grayed out. Alternatively, it starts with blank pages and as you start a gate it adds the icon.
When you do one level the icon turns colored and shows (emerald lion).
Finish tier 1 and you get a stamp (instead of a star) for tier 1.
If tier 1 has snarb you get the snarb boss stamp on that page also.
When gates go away you keep your passport history (stamps), progress still behaves the same as before.
Fill your stamp book! Collect them all!
Note: nothing *required* for people to do (no achievement), just something for completists.
I'm not sure if you realise this, but... There's this thing called Progress that people used to check all the time in the Personal Inspect pop-up. That tab gives information on which gates (in the current gate rotation) a player has unlocked (to disregard the Clockworks crown fee) and more recently, Shadow Lairs that have been unlocked.
EDIT: Mhm... oh yeah... derp