Is this game moddable today, without expansion? And how moddable it is, can you add new models or is it just retexturing?

I haven't really modded DS1 much, but...did check like ModDB or NexusMods?

I installed several mods from nexus and so far they seem to work.

Thanks for the answers, Obviously, I didn't phrased my question very well: I would like to make mods. I got impression that I will achieve that easier with older games. Many people pointed out that DS1 is easily moddable and I did play DS1 back in a day,so it seems as a good fit for what I want to achieve. I would just like to know is it possible to make mods for that game today?

I am no modder myself so I cannot garantuee it, but I do see mods being released even today, so I assume it's possible. There is software available to make the mods. I saw some linked on nexus. Also there are other tools you can use. Browse the current mods that are available and some will give information about which tools they use to create them.

I believe there are some tools to edit the .dres resource files. Forgot exact names but it's something like Tankviewer. Just Google it. From what I recall you'll need one to view and extract and 1 to edit the files. Just make sure to backup all original files.

Also, there are some really good mods out there like XP rings, extra inventory space, better textures, etc.

There's even a mod called Legenday something that you can install to play DS1 as a DS2 mod. I think it's basically playing DS1 maps with DS2 GUI and other features.

Dungeon Siege 1 had the editor freely released online and later updated to support legends of aranna content. It can be found online if you look around and there was also the dungeon siege university that goes into steps on how to use the tools, starting from basics with no knowledge and the courses eventually go into advance editing.

No, i kinda started playing with Unity.