Just how much of the game is predetermined?

[Joeygoku]

I'd imagine it's a system based off of an RNG with some prizes/cards (in tavern's case) having a wider range than others.

For Example:

5 guild chest prizes: leader card, Gold hero card, Purple hero card, 1.4mil gold, Treasure Map
RNG 1-10,000
Treasure Map: #'s 1-4500
1.4mil gold 4501-9800
Purple hero: 9801-9900
Gold hero: 9901-9999
Leader Card: 10,000

Only the RNG is decided before picking the prize