Source Level Editor (SLE)

Screenshot of SLE with a few brushes and player placed.

Developer(s)

Cvoxalury

Initial release

October 09, 2025
(2.104)

Stable release

July 2, 2026
(3.129)

Operating system

Type

Map Editor

Target engine(s)

Distribution

Freeware

Website

Website

Download

Latest Release

Version

3.129

Source Level Editor is a personalized fork of Hammer 4.x for Source created by Cvoxalury.

It's mainly intended for use with Source 2013 Singleplayer, and aims to make the basic mapping workflow more smooth and consistent.

Features

Documentation

SLE comes with offline help file, level_editor.chm. It is build similar to Hammer 3.x help file. Using the Help menu in the editor opens that file; it can also be opened in Windows directly. It contains the Setup Guide and User's Guide on most of new features and basic options and toolbars overview. The online version is hosted on SLE's repo's internal wiki.

Tools improvements

3-Point clipping is added, allowing for freeform clipping at any angle.
Face Edit tool supports texture shearing, randomized X/Y shifting, user-defined shifting step, extra Fit modes, quick Nodraw and Mark buttons, Grow/Shrink selection buttons.
Displacement Tool supports free dragging of vertices, 45° angle XY sculpting axis, fixed Face Normal axis.
Displacements and models can be exported to .SMD directly from the editor (requires rebuilding smoothing groups and resetting normals afterwards).
Multiple Cordons are supported.
Vertex Tool supports XYZ transform for vertices and collapsing edges with the Delete key.
Texture Browser includes Favorites materials list specified per-game.
Texture Browser can now Mark overlays and decals that use the selected texture, and Replace textures in overlays.
Soundscapes can be parsed and selected in the Sound Browser.
Background images: TGA artwork can be viewed inside the editor in 2D and/or 3D Views, resized, rotated, made translucent.
Limited support for Half-Life mapping: can save brushwork, entities and texture coordinates (but cannot load from WADs or use non-power of 2 textures).
Transform tool can remember settings and use Local Transform.
Rotating objects while holding Shift now clones them (with rotation applied). It also supports independent Rotation Pivot.
Overlays keep/update face assignment when using Clipper Tool on their solids.
Selected entities can be exported to a Commentary .txt file, working as a replacement for in-game Commentary Editor. Done via Tools->Export submenu.
Added option to Freeze/Freeze Unselected/Unfreeze All. "Frozen" objects cannot be selected in the viewports - this can be desired when working in densely cluttered areas. The objects can still be selected via Entity Report if necessary.
Brushes can be cloned while scaling or shearing them by holding Shift.
Portability: as of 3.129, the settings are stored in an .INI file instead of Windows Registry (the user can opt to keep using the registry with the -useregistry command line option)
Displacement vertices can now be frozen to keep them from moving while scuplting, subdividing or sewing. This works as a new mode of the Paint Geo brush, LMB to freeze verts (they get painted blue) and RMB to unfreeze.
Added experimental BSP Lighting Preview (Map->Light Preview). This is lighting method that existed in Hammer at least since 2003, but never worked. It requires the map being compiled with VBSP (it's okay if it leaks - it just needs the brushes), then the editor creates draft-quality lightmaps and overlays them onto the brushes.

Render improvements

3D Viewport can display the skybox, fog; can display scaled 3D skybox by marking 3D skybox geometry for display (no instancing required).
Material Proxies work in 3D View.
Several visual entities have previews, such as beams and spotlights.
Rendering of Tool Textures and Editor Objects is toggleable.
3D Flat view now uses unshaded outlined style instead of flat unshaded.

UI improvements

Hotkeys are now defined in an external, user-editable file and can be reassigned for every supported command.
Numerous tool and config dialogues have been cleaned up and/or expanded.
All Block Tool primitives are previewed before creation, including preview of arches and toruses.
Block Tool now supports creating brushes in 3D viewport.
Customizable 2D and 3D viewport colours (such as grid lines, the void, selected objects, instances) can be configured in the Options.
Run Map Dialogue (non-Expert) has been expanded with common compile options.
Sound Browser has FMod support allowing for MP3 playback, volume slider, and Stop button.
Texture Browser displays transparency, detail type, material shader, reflectivity; counts decals among used materials. The texture cache size can be set in the Options.
Flat View now previews complexity of models (tints them according to their triangle count).
Actbusy script is parsed for the drop-down menu for hint nodes.
World axii helper can now be seen in the corner of the 3D View.
Model Browser now displays attachments and can filter out Only Used models.
Overlays allow dragging their handles outside their assigned faces in 2D and 3D to make them easier to work with.

Stability improvements

Multiple crash bugs, performance slowdowns and limits from the original Hammer 4.x have been dealt with.
Vertex precision for solids is improved, in particular for Cylinders and Spheres.
Autosaves work on a separate thread, practically unnoticeable (no hitching/waiting for saving to be over). This is ported from Hammer-2013.

Full list of changes and features can be viewed in SLE features sheet.