Nguyen Thien invested $4,000 to purchase monsters, known as Axies, in the game, hoping to recoup it within the month and begin making profits thereafter. In two weeks, however, he has only got back 25 percent of his investment.

With six months of experience playing the game for someone else, Thien had made his own investment with three accounts using three separate devices.

But the main cryptocurrency in the game, called Smooth Love Potion (SLP), has plunged nearly 43 percent since July 13 to $0.198, making it hugely difficult to get back his money, far less make a profit.

“I make less than $80 a day after spending all my time on the game. At this rate, it would take me two months of playing non-stop to get my money back.”

Thien is one of 1.02 million players who have joined the play-to-earn game targeting profits.

Axie Infinity, co-created by Vietnamese gamer and entrepreneur Nguyen Thanh Trung, now requires a player to invest $1,000-1,200 to build his or her starting team of three Axies and use them to battle others for rewards.

A player uses the popular cryptocurrency Ethereum (ETH) to buy Axies but gets SLPs on winning. With the value of ETH doubling in the last three weeks and that of SLP falling, investors are not finding Axle Infinity a fun game anymore.

“I have spent nearly $1,500 on a standard team which cost less than $1,000 two weeks ago,” said Vu Nguyen. “I hope the SLP will rise again quickly, but this looks unlikely as it seems to be on a downward trend.”

Another concern for players is the latest update from game operator Sky Mavis. On Monday, the amount of SLP a player gets from winning a battle with the computer was halved from 50 to 25.

The reward for a battle between human players, however, was increased. Battling human players is considered more difficult.

“This means the operator is moving the game in a new direction to attract more real players instead of letting investors dominate the platform,” said Thanh Vinh, admin of a Facebook group of Axie Infinity players with more than 50,000 players.

Those who want to join the game only to make money will have to reconsider their move because of the cut in SLP rewards, he added.

Vinh said the policy change was the right decision because it reduces inflation of the cryptocurrency, making the game more balanced for new players.

Sky Mavis also explained its decision as a way to ensure the “long-term health of the system” as the amount of SLP created recently was many times more than the amount spent.

Other players, however, consider this a negative move.

Nguyen Manh, a game developer in HCMC, said that a play-to-earn game is a small economy, and developers should not interfere when there is a rise or fall in the cryptocurrency.

He compared the mechanics of the game with how farmers produce their crops. The more crop farmers produce the lower their prices will be because of a glut, but this was a natural principle and the market would adjust this by itself.

“It is wrong for developers to cut the reward by half. It is similar to forcing farmers to produce only half of what they can. That is negative,” Manh said.

The changes will push a number of players leave the game, he said, adding that developers should have created new events for players to spend their SLP on to reduce inflation.

Thinh, meanwhile, is considering changing his strategy to recover his investment faster.

“I’ll focus on one account to make them stronger and battle other players.”

Nguyen, however, said he would stop playing after recouping his investment.

“This market is too difficult for me to make money.”