What can you do?

You can do many things with private server. Some can be done purely server side, others need to be done to client as well.

For example, if you create custom monster (model as well as stats) you will have to update the client so that users can see the new model.

Weapons with custom stats, and monsters with customized stats, drops and names etc can be done entirely from the server.

You can remove, change, replace or even add spawn points and times, all from the server.

A GM character can start custom event spawns without access to the server.

Your biggest limitation, if you open your server to the public, is that increasing the XP rates will cause players to level "too fast" and the server protection will interpret this as hacking and kick your players off every time they kill something.

You can globally increase XP rates, and you can change the XP gained for killing individual monsters. Either way, you need to watch for monsters giving more than a single level up from one kill. And remember that many characters can AOE, killing many monsters with one hit.

If you are playing on your own server, or running a LAN party, you can disable all server protections in the servers hotuk.ini ... but if you open such a server to the internet, it will be brought down by hackers pretty quick.

You can modify the content of NPC stores, change their location, add new stores with new inventories for sale etc.

You can create custom drops, and custom items for donators... but you will still have to watch the stats, because if you get into a bidding war for greater and greater stats, you will have to disable server security, or suffer many hacking alert log entries, and player DCs from leveling "too fast".

Also, if you wish to add custom weapon shapes, models, glow effects etc. you will have to modify client side, and there is limited space in the game.exe to place new texture and model file names. You may have to replace some standard items you don't intend to use.

You will need to become fairly proficient with a HexEditor, and possibly a debugger / disassembler such as OllyDebug to locate the areas in the game client you want to change.

From the server, most configurations are in plain text files similar to Win9x .inf files or Win3.x .ini files... but having a translator for the Korean and Japanese text in them would be handy. People here will advise upon the information as it looks with only European characters shown... but if you change the character set to Korean or Japanese these files make more sense... at least, they can be readily translated.

The server files usually used, are modified versions of a leeked Japanese server... most people use either the Korean client, or a modified version of either Korean or Japanese clients.

Neither client nor server are UTF aware, and both will assume either Korean or Japanese language installs... but most files in the RFT thread have been modified to show English regardless of thiis internal working. This is still just a front for players, internally they are working in a far east asian language. ;) learn to live with it.

You will not get much responce here from general "How do I do everything possible" questions... but since I'm pretty new here too, I will tell you this much.

Follow one of the pinned guides. Set up as much as you can, and use the search function "such as it is" before asking "I'm stuck trying to make *blah* work". That kind of question will get a better responce than just "tell me everything you know" questions.

Good luck unzubaru, and I'll see you around here.