Hi PHeMox,
If you plan on selling your software in the US or doing business in the US under your company's name, then yes I would recommend registering with the USPTO.
As I said it will cost you around $500 for an IP lawyer to register your trademark. Assuming there is no opposition to your name. I.E. Opposition is when your mark infringes on some one elses trademark.
A registered trademark is a very valuable thing. Having it registered mean's you can also sell it, when you sell your IP, Brand or Company to some one else. Trademarks have the value of the registration plus all the intangible good will related with the trademark / IP.
For example you have some success with "Potatoe Guns" and you want to sell that IP to some one else. If the trademark is not protected then there is no protection for the buyer. With no IP protection someone else could legally use the name "Potatoe Guns" for another game and confuse the buying public, hell, if they register the trademark and you dont they could then steal the trademark and your goodwill. This would kill most IP sales. So having a simple legal instrument like a trademark that can be legally transefered and has all the rights afforded a trademark, is actually what a buyer of IP's would want.
Basically if you are serious about selling software in the US, and your trademark is important to you, and if you can afford $500 then you should consider it.
Ken