There is nothing "wrong" with your question, per se, it is just a normal software recommendation question, but it borders on "too-broad" and some people don't like software recommendations for that reason. (For more information about how the software recommendation tag is/should be run and tips on how to ask a good soft-rec question see these two meta posts: How to run the Software Recommendation tag and the answer to Just lets drop the software recommendation mess.)
The downvote might have been from one of those people, and that is a perfectly valid reason to downvote. So were the downvotes you cast on the answers, perfectly valid reasons to downvote. Not everyone would have, but still perfectly valid.
Now, could the downvotes have been from one of the answerers? Yes, it could have. Does that make it an invalid downvote? No, it doesn't. They are free to vote on a post for (pretty much) whatever reason they like, as long as it doesn't extend into voting for or against a specific user. That is called targeted voting and is against the rules of the site. Moderators cannot see who voted on a post1, nor can they remove votes on a post2, so no, the downvote cannot be removed, nor would its removal be in line with the way the site works.
In your participation in the Stack Exchange network you will get downvoted, and unless the downvoter leaves a comment explaining your downvote, there is nothing you can do about it. As long as you are sure that your question/answer is correct and falls within the scope of the site the best thing you can do is ignore them.
1 Moderators can sometimes see groups of targeting votes to and from users, but not individual votes.
2 I suppose (theoretically) we can mass remove votes by deleting users, but that wouldn't really serve here, even if we could see who voted.
Now, a tip for your specific question: I suggest you go into a bit more detail about what a rogue like game is and what you expect for "side scrolling". Maybe give an example?