How to write Sitecore custom engagement rule condition

Here is sample custom enagement rule

public class CustomEngagementValuePointsCondition<T> : OperatorCondition<T> where T : RuleContext
    {
        public int Value
        {
            get;
            set;
        }

        protected override bool Execute(T ruleContext)
        {
            int value = 0;
            try
            {
                if (Tracker.Current.Contact != null)
                {
                    value = Tracker.Current.Contact.Value;  
                }

            }
            catch
            {

            }
            switch (base.GetOperator())
            {
                case ConditionOperator.Equal:
                    return value == this.Value;
                case ConditionOperator.GreaterThanOrEqual:
                    return value >= this.Value;
                case ConditionOperator.GreaterThan:
                    return value > this.Value;
                case ConditionOperator.LessThanOrEqual:
                    return value <= this.Value;
                case ConditionOperator.LessThan:
                    return value < this.Value;
                case ConditionOperator.NotEqual:
                    return value != this.Value;
                default:
                    return false;
            }
        }
    }