XP System 2.0 - Rewarding Players Effectively

Today we are making a change to how experience (XP) is awarded for gameplay. This blog post explains (with charts, courtesy of Mr. Dataman!) what is changing, why it is changing and what we hope the impact will be. Your feedback is welcome heavily encouraged as always! 

Why are we changing?

The XP system is a fundamental component of Gods Unchained. As well as measuring your level of mastery of the game it is the mechanism by which you will collect core cards. 

Part of the balancing beta is about understanding how we can use the blockchain to reward you with real value for playing the game. To be able to do this we need to ensure the system is safe from vulnerabilities as some users will find a way to exploit them if it is profitable. Just as important is ensuring player incentives are aligned with our goals of a fun game.

Thanks to our incredible beta testers who have been generating useful data and giving insightful feedback, we have identified some issues with the current system.

Issue #1: Toxic quitting

In the original XP system, both players received 0 XP if a match finished before round 5. As a result, some players would quit at round 4, just to prevent their opponent receiving XP. Even more extreme, some players were conceding at the mulligan phase due to a bad draw. We will never be able to prevent ragequitters from ragequitting in totality, but we can make it a ‘bad move’ from a game theory perspective and prevent punishing the player on the other end. We want to maximize the players time in the game; not the time they spend queuing. This was why we made the quick-fix to grant the winner XP if their opponent concedes before round 5. Since making the change we have seen the % of games that last to round 5 increase by 7%. 

Issue #2: Meta-distortion

One of our key design principles is to create a well-balanced meta so that marketplace card demand is not skewed to a small subset of cards. The current XP system gives the same amount of XP whether you finish on the 5th round or the 10th round. This strongly rewards players who use fast decks that force a result early, allowing them to re-queue as soon as possible.

The New System

Experience is awarded based on two components:

• A constant value per round completed which rewards both players for time in game
• A fixed bonus for winning which rewards skilled play

Same in the current system, if you concede before round 5 then the XP you have earnt will be forfeited.

Impact

“all models are wrong, but some are useful” 

- George E. P. Box, an o.p. statistician.

We built a prototype to model the impact of these changes. Even the best models only approximate reality, meaning what follows are our best prediction based on the data available to us and some simplifying assumptions. 

Assumptions

We assumed that:

• Matchmaking will result in 50% win rate 
• Matchmaking will be random i.e. win trading will be impossible
• Matches will follow the existing distribution of final rounds, except no match will finish before round 5 or after round 16 (see chart)
• Average game duration:
• 30 seconds to queue + get connected
• 15 seconds for mulligan phase
• 1 min per round (see chart)

Data

Impact #1: Toxic quitting

There should be no way to ‘penalize’ the winner by strategically conceding at a certain round. Assuming a player wants to minimize the XP differential they will wait until round 5 to concede because the loser gets 0 XP if they quit before then. After round 5 the difference between winner and loser XP is fixed. The new system, therefore, looks the same as the old (quick-fixed) system from this perspective.

Impact #2: Meta distortion

The XP system should not increase the relative value of different deck types. The below chart compares the old to the new system. The columns show how much XP you would earn on average (i.e. assuming 50% wins) if you finish games in that round. There is still a slight advantage to finishing a game early as the win bonus is fixed, however, the variation is much smaller:

• 16% better to finish in round 5 vs round 16 for the new system
• 200% better to finish in round 5 vs round 16 for the old system

Impact #3: Concede at the right time

Another design goal is that games should last as long as they remain interesting and fun. We don’t want you to play past the point where you know you have lost, just to earn XP. Similarly, there is nothing more frustrating for the winner than an opponent who refuses to concede, wasting everybody's time.

The chart below shows whether it is more efficient to concede and start a new game or continue playing. Each line shows the difference in XP earn rate between staying in the game and conceding and starting a new one, based on the current round and the likelihood you think you can win. When the line is above 0, it is better to stay in the game. This means that:

• It is best to quit at the Mulligan phase if you think you have <30% chance of winning
• If you are in round 4 you should wait until round 5 before conceding so that you don’t forfeit the XP you have earnt
• As the game progresses even if you think the chances of getting the win bonus are slim it is better to continue playing because the time left is short

Remember we are assuming you have a 50% chance of winning in the new game and that the game will finish in the average time which may not be true when you are making concede/play on decisions.

Impact #4: No change to overall leveling rate

Finally, we do not want to change the overall leveling rate. Assuming the games finish as shown above then the winner will get 350 XP and the loser 250 XP on average, exactly the same as the current system.

The Future

We will continue iterating and improving this system based on your feedback and trends we see in the data. We will also look to extend XP bonus to other areas such as:

• Good play (e.g. opponent god health was low)
• Exploring the game more (e.g. playing new gods, new decks, etc)
• Time-based rewards (e.g. first game of the day)

If you have feedback for this system, we’d love to hear it here or in our Discord. Do you think these changes will positively impact gameplay? Have we missed something? How else would you like to see XP awarded?