Add 1 or more of these VARIATION SHOWCASES to the players’ exhibition halls. Possibly on top of base game showcases, to replace those.

The 6 new showcases are:

Showcase ANTIQUITY (2 spots) for 5/4/3/2/1(0) victory points: Who has the oldest year in the right side spot?
Showcase UNIQUE DECADES (2 spots): Each decade must differ from the earlier placed decades of all players (including yourself) in this showcase. (With 4, 3 or 2 players, only the respectively middle 8, 6 or 4 decades are allowed. (So with 2 players only the 30s, 40s, 50s and 60s.)
Showcase SHORT ERA (3 spots) for 5/4/3/2/1(0) victory points: Who has the smallest difference in years between the left and the right side spot.
Showcase ONE DECADE (3 spots): All cards in this showcase must have the same decade.
Showcase SPREAD THE YEARS (4 spots): The difference between neighboring cards must be 20 years or more.
Showcase LINKS (4 spots): Each 2 neighboring cards must have OR the same continent OR maximum 5 years difference. (or both)