Real way to prove that the weapon sync is OK - throw some hardcore pros in your servers, let them fight, ... , profit
Exactly this. The player base you're looking to draw in would be from VC:MP, Deceifer. There are relatively few people out there who search for an online multiplayer mod for Vice City on a day to day basis, so drumming up public support for a relatively unpopulated project is hard. Instead of just looking to the wider public, I suggest looking to VC:MP players.
Nowhere on the internet is there such a group of Vice City enthusiasts than there is here. As Las3r said, if you get a few well known members of the VC:MP community to try your mod and approve, buzz about it would go through the roof. Here's a few insights of mine on what's important and what isn't, that I've drawn from years of playing here:
Important:
- Weapon sync. Above all else, the number one complaint of VC:MP players and those who refuse to play it is the bad weapon sync. If you were to prove yours to be significantly better, you'd already be half way to gaining as much popularity as VC:MP.
- Stability. Previous versions of VC:MP were littered with crashes, players would crash every half an hour or so. The playercount suffered because of this. Since R2 came out, containing very few crashes, the playercount has shot up. (Not completely due to this, but it is certainly a contributory aspect)
- Anti-cheat. Hackers drive people away faster than a stink bomb in an art gallery.
Not important:
- A thousand cool features. The most popular servers in VC:MP are simple as fuck. They allow for pure DM, in a safe (hacker free), stable and free environment. As long as there are cars, guns and other people, players will find a way to have fun.
What I'm trying to say is that it's better to get a stable, sturdy, simple modification than it is to have one with a bamboozling number of embellishments around a core that doesn't work properly. The core is the most important part.
I suggest looking at VC:MP's functionality (best to look at the squirrel wiki for that), see what you can match up to and then focus on a select few improvements or new features; there needn't be anything entirely revolutionary in the first release of a new modification. (I know you already released one and a patch, but let's forget about those :p)