ml-agents/UnitySDK/Assets/ML-Agents/Examples/Soccer/Scripts/SoccerAcademy.cs

using UnityEngine;
using MLAgents;

public class SoccerAcademy : Academy
{
    public Material purpleMaterial;
    public Material blueMaterial;
    public float gravityMultiplier = 1;
    public bool randomizePlayersTeamForTraining = true;

    public float agentRunSpeed;

    public float strikerPunish; //if opponents scores, the striker gets this neg reward (-1)
    public float strikerReward; //if team scores a goal they get a reward (+1)
    public float goaliePunish; //if opponents score, goalie gets this neg reward (-1)
    public float goalieReward; //if team scores, goalie gets this reward (currently 0...no reward. can play with this later)

    void Start()
    {
        Physics.gravity *= gravityMultiplier; //for soccer a multiplier of 3 looks good
    }

    public override void AcademyReset()
    {
        Physics.gravity = new Vector3(0, -resetParameters["gravity"], 0);
    }

    public override void AcademyStep()
    {
    }
}