I think so many developers, especially indie developers, get caught up in this idea that they need hardcore gamers to test their games for them and help them find bugs. There is certainly a need for that type of testing. There is another type of testing that tends to gets ignored. The issue of playability, is the game simply fun to play and do things make sense, and adaptive difficultly, does the game scale difficulty up or down well based on the playing style to keep the user challenged without frustrating them. Sometimes developers get very attached to their game or portions of their game and think that there is nothing wrong with them and that area is the best part of the game. The problem is that you and your team have been working with the game so long that it makes complete sense to you and seem logical and effective, but those on the outside and those who are not hardcore gamers are left scratching their heads wondering what the developers where thinking and what in the world are they suppose to do next to get to the next point in the game. I have found this myself in several games and I have been playing games for 30+ years. I have even had experiences where it seemed like the game was cheating or taking cheap shots to the point where I wanted to skip that section because it was no longer fun to play. So you have to wonder in situations like that if they bothered to have anyone from the outside actually play and test the game before they released it.
I think that for indie developers, it is important to appeal to as large an audience as possible given the type of game that is being developed. The biggest problem indie developers face is people even being aware that they exist and that they have a really cool game to sell to people. Given that exposure is a problem, indie developers need to work hard to make sure they turn every possible sale into an actual sale or user of the game.
The question becomes, what is the best way to do that? There is no one single snap answer that works in every single case. I will mention a few things to try that can certainly point you in the right direction. The first would be a usability testing round after the beta testers have helped to squash the major bugs and it becomes harder to find them. Once you get to that point it is time to do the unusual thing and look for testers who you might not think of as a target for the game or those who you wouldn't normal consider to test the game before release. The best thing a developer can do is to grab their mother or a female friend of their wife/girlfriend and have them sit down and attempt to play the game with absolutely no more instructions than enough to get the game installed and running and nothing more. Then carefully watch them play and notice the pauses and other cues as they are trying to figure out how to play the game and what the goals of the game are given just what is presented to a random user who might purchase or use your game. Notice where it takes them longer and more attempts to get through areas and realise that the game isn't adjusting for their skill level or their style of play or whatever. Take note also when they become frustrated and realise one of two things are happening. Either they don't understand what is expected to get past this point in the game or that game has ramped up the difficulty level to far to fast or in a way that doesn't match their playing style. It is best to just watch them play and not comment or offer advice. The other thing is when they are finished ask them what the liked most, least and what one or two things would they change about the game if they could make any change they wanted. You just might get a few answers that surprise and hopefully help you build a better game.
This can't apply to every type of game out there. For example a real time strategy game would not be something your mother would have any interest in playing most likely, but if you can find those non-standard tester during development they can help you make a better game and reach a larger audience than you might have before.
Let us know your thoughts on this. If your a developer do you use a number of unusual testers, and if not have you ever thought about using them? If you are using unusual testers how have they worked out for you, and how do they help you in the development of your game? Let us know.