Personally, I think your gigs are pretty cool. I wish I had a need for your level gig. I’m a long time gamer and if I had the skills to work on a game and needed help, I would hire you. You do need some reviews just to help build a reputation and that’s tough. Your prices are very competitive. I can think of 3 ways you might be able to improve your chances of sales.
One, you need to find ways to really show your gigs off in a community that is all about games and game design. Look for forums dedicated to that if you aren’t already on some. Whatever you do, though, don’t jump right in with ads. Start getting involved in those forum communities and contribute interesting information, help other people for free, offer advice to new designers, etc. After you are known, then start dropping links in your signature to your gigs and pull back on some of the free help. You might get some like-minded people without the time or skills to do what you do who will hop over to Fiverr and give you a chance.
Two, if you can find a way to really show off what you do, that will help. The best thing would be to actually design something playable even if it’s only a few minutes to finish. Tell people right in your gig description that you’ll send it as a sample to interested buyers. Make them want more so they have to buy a gig to get more. If you can’t do that, at least make some videos of your work and put those on YouTube. Put up links in your gig description and send interested buyers a link to your YouTube channel.
Three, make a gig or two that is unique and interesting but different from the others. It doesn’t really matter what as long as it’s unusual and gets attention. The Fun and Bizarre category is a wide-open area that is under-utilized. The point is to get people to click on those gigs and make it to your profile. Of course, they still need to be real gigs that you can actually do, but put that young mind to work on what will make people want to click.