feat(meta): add proper readme

README.md

@@ -1,8 +1,101 @@
 ![Momentum Mod](https://momentum-mod.org/assets/images/logo.svg)
 
-> *Momentum Mod is a standalone game built on the Source Engine, aiming to centralize movement gametypes found in CS:S, CS:GO, and TF2.*
+> *Momentum Mod is a standalone game built on the Source Engine, aiming to centralize movement gametypes found in CS:S,
+CS:GO, and TF2.*
 
-Lumper is a .NET based tool developed by the Momentum Mod Team for manipulating BSP files, the Source engine's compiled map format.
-It is aimed at map reviewers and porters, giving them the ability to analyse and tweak BSP files without having to decompile then recompile.
+<h1 style="display: flex; align-items: center; gap: 0.5rem;">
+    <img src="images/Lumper.svg" alt="Lumper Logo" width="32" height="32">
+	<span>Lumper</span>
+</h1>
 
-Potential contributors are welcome to reach out to us in the [Momentum Mod Discord server](https://discord.gg/momentummod).
+Lumper is a program for viewing and manipulating the various "lumps" that constitute Source Engine map files (BSPs).
+
+It is *not* a map authoring tool like Hammer, which operates on map source files (VMFs) that are then
+compiled to BSPs. Lumper is intended for small, destructive tweaks to existing maps. It's most similar to
+[VIDE](http://www.riintouge.com/VIDE/), which is unfortunately closed-source, inactive, and doesn't support more recent
+BSP versions.
+
+## Features
+
+### Entity Editor
+
+View and edit the contents of the editor lump à la EntSpy/VIDE. Includes a "Raw Entities" view for editing the entire
+lump as plaintext.
+
+![Entity Editor](images/entity_editor.png)
+
+### Pakfile Editor
+
+View and edit the contents of the pakfile lump with a built-in file tree, text editor, and VTF viewer.
+It supports import files/directories, exporting to the filesystem, and can automatically update references to paths in
+other lumps when items are moved.
+
+![Pakfile Explorer](images/pakfile_explorer.png)
+
+### Texture Browser
+
+Displays every VTF file packed into the pakfile, like Hammer's texture UI.
+
+![Texture Browser](images/texture_browser.png)
+
+### Jobs
+
+Jobs are a way of automating repetitive tasks, particularly Momentum map porting. Multiple jobs can be ordered
+sequentially, and export/imported as JSON "workflow" files. The current jobs we support are:
+
+- __Stripper__ - Apply [Stripper:Source](https://www.bailopan.net/stripper/) configs to a BSP. What is usually done at
+  runtime on a server via SourceMod can be *permanently* applied to the BSP file!
+- __Replace Textures__ - Update the texdata lumps to refer to different material files. Supports regex!
+- __Run External Tool__ - Runs a given executable on the loaded BSP.
+
+![Jobs](images/jobs.png)
+
+### Compressed Exporting
+
+Lumper can load and save LZMA compressed BSPs, including the pakfile, producing the same result as `bspzip`.
+
+### JSON Diffs
+
+Lumper can serialize the contents of the BSP to JSON files, helpful for analysing a BSP in a human-readable format and
+diffing BSP versions in Git.
+
+## Download
+
+See the "Releases" tab on the right! This program is very new, and we don't currently have any kind of auto-updater, so
+worth checking back here for updates regularly.
+
+## Momentum
+
+Lumper is developed by the Momentum Mod team and contributors. On Momentum frequently need to adjust BSPs slightly when
+porting. Out of respect for mappers we avoid modifying the original BSP as much as we possibly can. Manipulating
+existing BSPs is much less intrusive than decompiling, adjusting, and recompiling. Lumper lets us:
+
+- View the important parts of the BSP for moderation during map submission, *especially* the pakfile lump.
+- Remove packed assets we shouldn't be storing/serving (usually Valve stuff, e.g. CS:S textures packed for use in
+  CS:GO).
+- Tweak entities to better use native Momentum entities.
+- Move pesky music files to the `sound/music/` directory of the paklump so they're affected by the right volume sliders
+  ingame.
+
+## Technical Details
+
+Lumper is written in C# 12, targeting .NET 8.0. It's divided into three subprojects:
+
+- __Lumper.Lib__ - Library for BSP manipulation, with minimal dependencies. Also includes jobs. Rather than do VTF
+  handling oureslves we use [VTFLib.NET](https://github.com/momentum-mod/VTFLib.NET), which provides .NET bindings
+  for [VTFLib](https://github.com/NeilJed/VTFLib).
+- __Lumper.UI__ - GUI frontend using [Avalonia](https://docs.avaloniaui.net/). It uses an MVVM architecture with XAML
+  for layouting and [ReactiveUI](https://www.reactiveui.net/) for reactivity and view ↔ viewmodel binding.
+- __Lumper.CLI__ - Simple CLI application for repetitive tasks, especially jobs. It's WIP and as of writing, barely
+  functional.
+
+See [our wiki](https://github.com/momentum-mod/lumper/wiki/Dev-Home) for more info!
+
+### Contributing
+
+We are happy to accept contributions! Whilst we prioritize Momentum-related use-cases ourselves, we hope this tool is
+helpful to anyone using Source 1, and we welcome contributions and bug reports from people not involved with
+Momentum.
+
+Besides this repo the best way to contact us is on the [Momentum Mod Discord server](https://discord.gg/momentummod),
+ideally in the `#tooling` channel.