Detecting and preventing cheating in a location-based game
Systems and methods for detecting and preventing cheating in a location-based game are provided. In particular, a server-side statistical cheat detection algorithm can be implemented upon receiving a player request to perform a game action. A given dataset describing the respective times and locations of previous game events performed by the player can be analyzed to determine a probability that such game events represent legitimate gameplay. The determined probability can affect whether the player-requested game action is effectuated or can influence a number of points awarded for completion of the game action. An example system includes a host server and a client device in communication over a network.
1. A computer-implemented method for discouraging cheating, the method comprising:
hosting, by one or more computing devices, a location-based game;
logging, by the one or more computing devices, event locations and event times for a plurality of game events, each game event associated with one of the event locations and one of the event times;
receiving, by the one or more computing devices, a request to effectuate a requested game action, the request having a request location and a request time;
calculating, by the one or more computing devices, an inter-event velocity based on a difference between the request location and at least one of the event locations and difference between the request time and at least one of the event times;
inputting, by the one or more computing devices, the inter-event velocity into a probability function to obtain an event probability; and
determining, by the one or more computing devices, whether to effectuate the requested game action based on the event probability.
2. The method of claim 1 , wherein the event probability represents a probability that the inter-event velocity reflects legitimate gameplay.
3. The method of claim 1 , further comprising:
in response to determining to effectuate the requested game action:
modifying game data to effectuate the requested game action; and
creating a database entry reflecting the requested game action in a game database.
4. The method of claim 1 , further comprising:
determining a number of points to reward to a player for a completed game action by multiplying an expected number of points by the event probability.
5. The method of claim 1 , further comprising:
in response to determining not to effectuate the requested game action:
transmitting, by one or more computing devices, an indication that the game action was denied.
6. The method of claim 1 , wherein the probability function includes a velocity threshold term that reflects a boundary between legitimate gameplay and cheating.
7. The method of claim 6 , wherein the probability function comprises a logistic function with the constant e raised to a velocity difference term, the velocity difference term being the velocity threshold term subtracted from the inter-event velocity, such that the probability function trends toward zero as the inter-event velocity increases in magnitude with respect to the velocity threshold term and trends towards one as the inter-event velocity decreases in magnitude with respect to the velocity threshold term.
8. The method of claim 6 , wherein the probability function is a logistic function that provides an output based on the difference between the inputted inter-event velocity and the velocity threshold term.
9. The method of claim 6 , wherein the velocity threshold term is modeled on gameplay data previously received by a game server.
10. The method of claim 6 , wherein the velocity threshold term is generated by training a supervised binary classifier on a set of game data previously classified as indicative of either cheating behavior or non-cheating behavior.
11. A non-transitory computer-readable storage medium comprising instructions executable by a processor, the instructions comprising:
instructions for sending, from a client device, event locations and event times for a plurality of game events, each game event associated with one of the event locations and one of the events times;
instructions for sending a request to effectuate a requested game action, the request including a request location and a request time;
instructions for receiving a decision of whether to effectuate the requested game action, wherein the decision was determined by:
calculating an inter-event velocity based on a difference between the request location and at least one of the event locations and difference between the request time and at least one of the event times; and
inputting the inter-event velocity into a probability function to obtain an event probability; and
instructions for displaying a result of the request based on the decision.
12. The non-transitory computer-readable storage medium of claim 11 , wherein the event probability represents a probability that the inter-event velocity reflects legitimate gameplay.
13. The non-transitory computer-readable storage medium of claim 11 , wherein the instructions to display the result comprise:
instructions for receiving modified game data describing the effectuation of the requested game action.
14. The non-transitory computer-readable storage medium of claim 11 , wherein the instructions to display the result comprise:
instructions to display a notification of a number of points awarded to a player for completing the game action, wherein the number of points was determined by multiplying an expected number of points by the event probability.
15. The non-transitory computer-readable storage medium of claim 11 , wherein the instructions to display the result comprise:
instructions for displaying an indication that the game action was denied.
16. The non-transitory computer-readable storage medium of claim 11 , wherein the probability function includes a velocity threshold term that reflects the boundary of legitimate gameplay and cheating.
17. The non-transitory computer-readable storage medium of claim 16 , wherein the probability function comprises a logistic function with the constant e raised to a velocity difference term, the velocity difference term being the velocity threshold term subtracted from the inter-event velocity, such that the probability function trends toward zero as the inter-event velocity increases in magnitude with respect to the velocity threshold term and trends towards one as the inter-event velocity decreases in magnitude with respect to the velocity threshold term.
18. The non-transitory computer-readable storage medium of claim 16 , wherein the probability function is a logistic function that provides an output based on the difference between the inputted inter-event velocity and the velocity threshold term.
19. The non-transitory computer-readable storage medium of claim 16 , wherein the velocity threshold term is modeled on gameplay data previously received by a game server.
20. The non-transitory computer-readable storage medium of claim 16 , wherein the velocity threshold term is generated by training a supervised binary classifier on a set of game data previously classified as indicative of either cheating behavior or non-cheating behavior.