Upon connecting to the server, you are greeted with a slot machine, along the phrase that you're playing the "Liquidity Crash Game", I was trying to hint at the fact that the slot machine is using a LCG (Linear Congruential Generator) as its RNG.
The reward from the slot machine is calculated based on the amount of consecutive numbers. In particular, the amount bet is multiplied by the following table.
| # Numbers | 1 | 2 | 3 | 4 |
|---|---|---|---|---|
| Reward | 0 | 2 | 10 | 100 |
Every turn you take at the slot machine reveals a sequence of 5 truncated RNG outputs. Breaking LCGs is a widely discussed topic, so I'm not going to dive too deep into that, msm's writeup on this is worth a read.
Using the numbers outputted by the RNG (they're shown to you inside the slot machine) to reconstruct the state of the LCG, you're able to predict the next sequence of numbers, revealing whether you're winning or not.
The strategy then, is to just bet whenever you're winning something (>=2 consecutive numbers).
Reaching a balance of 10,000,000 coins reveals the flag.