I understand that you want to keep your hard work to yourself and I get that a hacked/modded game will produce completely useless bug reports.
But lets be honest, this is the internet, the second you release the binary there will be some lurker decompiling the code to mod in pink laser resilient hair that grows on ships as long they're watered in orbit of planet with water, or whatever. And he'll probably share it with his pink hair loving friends. I just don't see how that affects you negatively in any way and therefore justifies any time put into security measures. Legally you should be on pretty solid ground, if someone distributes your code you have the power to have them shutdown. But if you do, the only effect that will have is that no one will show you the mods they made.
I'm not sure if this whole line of thinking is that healthy. The people most likely to mod your source code are the people who love the game, who want to add features they want while playing, just like you already do. The devs over at Dwarf Fortress seem to be in a very similar situation and they just ignore it for the most part, they say they never touch the mods and they won't read bug reports from modded versions. The lack of security measures doesn't look like its hurting them. In contrary, there are a plethora of tools to make the game more accessible for people. There are graphics packs, 3D visualizers, data visualizers, templates and other automation tweaks. By doing nothing more than tolerating the behavior, I feel, the community of Dwarf Fortress became so much richer.
I mean, in the end this is your project and if in 2 years someone puts out a memory access library it is completely in your right to have them take it down. That will at least limit it's spread. But I would urge you to at least consider if such an action is actually worth your time.