I hate to say it this way, but this market is tough. Timing is everything and the best offers speak the loudest. There could have been an offer the day you saw the home, maybe not. Buyers are in the market now and believe it or not, homes that have been on the market forever are getting sold and sometimes with multiple offers. That is why offers need to be based on how much you want the property and how fair the price is. There is always the risk that someone will outbid you.
Homes that are priced well and are attractive to the market for one reason or another (maybe even needing a lot of work) go fast. Some wait for a while.
It doesn't mean there are games being played. This happens. However, it is not required to disclose multiple offers or even that there are other offers. In most cases, it is a good idea, because you get the best deal for the client, but there are two sides to every coin. Not required at all.
Keep your eye on the property. Sometimes offers don't go through. Put yours in as a back up and keep looking. There is a lot out there. It may sound trite, but maybe this was not the house for you, even though you wanted it to be. Your house may be waiting for you to find it.