Oh I see, you want to reverse engineer it. The URL is created via Firebase's Dynamic Links, which stores the JSON template for the game setup to be retrieved whenever the link is followed.
Hypothetically you could call the Dynamic Links API to create one, the JSON template itself isn't all that obfuscated. Here's an example:
{
"created": "2022-01-14T10:49:57.807500", // Timestamp
"createdIn": "1.5.9", // App version number
"maxCrewSize": 50, // Optional, defaults to 50
"name": "GG Season 2", // Optional, defaults to 'ruleset'
"ruleset": "GG Season 2", // Optional, defaults to latest ruleset from setups file.
"strat": "m", // One of c(row), m(ask), r(am), or t(ome).
"deployment": "c", // One of c(row), m(ask), r(am), or t(ome).
"schemePool": [ // 5 different 0-indexed scheme numbers.
9,
0,
5,
3,
4
]
}