• good design
• without fatal errors and critical SC's
• can be finished by many players

Difficulty

• Map difficulty must be balanced. Don't use very sharp difficulty changes. If you're making an easy map, then it must be easy from start to finish, don't make easy map, which will be easy at start only.
• We've written an article where you can see our criterias of maps difficulty, you can read more about it here

Length

• Minimal map length is 1 minute with ideal run
• Optimal length is 1.5-2 minutes with ideal run
• Maximum length is not limited, but we recommend you not to make very long maps and especially don't make very long and difficult maps

Routes

• Don't make many routes on map, because it will causes problems with demo submitting process. Our LAN server is not able to automatically detect route used in demo, so player have to rename demo file manually and it makes us unhappy, because some demos with routes have wrong names.
• In addition to previous rule, please don't make many routes with different difficulty, because it works very bad on public servers

Design

• Map must have an idea and all design must be built from this idea. Please be logical and strive for realism. Don't use abstractionism.
• Use high quality textures and try not to use old textures from Half-Life 1 or other games released 15 and more years ago, because it looks ugly
• Try to use unique textures or make changes in textures created by others.
• If some texture is used to fill big area, then you must use tiled texture or make something to hide joints
• Please be sure that blocks passed by players are not merged with walls or background.
• Check all bhop blocks to prevent texture bugs.
• Movable blocks must be designed diffirent related to fixed blocks. Be sure that player can see what type of block he jumps to. Also use different design for blocks with different purposes
• Don't overdo texture scaling because it can adversely affect video quality.
• Use strict square design with grid arrangement only if it's your map concept. Otherwise it looks bad and not realistic. Bring a little chaos in your blocks
• Calculate maximum viewable distance on your map to prevent frustum culling in every point where player can be.
  

Lighting

• Every light on your map must be properly designed. If you're using light or light_spot entity, then you must place there something that glows. It can be a flashlight or torch, or maybe something else that would look perfect in your concept. So, don't use light and light_spot without an object.
• Use lights and shadows in your map and don't make maps which use light_environment only.
• Don't make very bright or very dark maps because every player has a unique monitor, so very dark map which looks cool on your brightful monitor can be unplayable for others. Also don't forget that time of day when player passes your map matters too.
• Be sure that player can finish your map without nightvision or flashlight.
• Don't create a lot of light's with flickering effect, because Half-Life will process every light in every frame and it will cause fps drops.

Sound and ambience

• Don't use music on your maps because many players like to play with music which they like and it can be different from your taste. So don't force players to use stopsound. You can use neutral ambience (for example sounds of water, wind or something like this)
• Avoid using screamers if your map is not in horror style.
• Use sounds to bring a realism to your map. So bonfire or torch must be with fire sounds.

Entity

• Be sure that you map doesn't exceed the limit of entities. We're rejecting all maps that require special settings to run.
• Use func_illusionary instead of func_water to create big water areas, because func_water causes a fps drops.
• Don't use a func_illusionary entity for object which can be used by player. For example, if player can use a torch to jump then it can't be func_illusionary.
• Use a corresponding trigger_hurt for fire or other aggressive environment to bring more realism to your map.

LJ and other elements of a map

• If you're making an easy map then don't create blocks possible to jump with CJ only, because novices who play easy maps can't do it.

Wpoly, epoly, dynamic textures

• Please be sure that from every point of your map wpoly counter is not greater than 2500 polygons. To fit this limit you must divide huge ares into small rooms and correctly connect them with corridors or tunnels.
• Don't make high poly details with brushes and use models instead. But don't forget that models are hard to find and they have problems too, for example with lighting.
• Don't use a lot of animated textures on your map because it will cause fps drops..

Rooms

• Don't make a map with only one room. The Goldsource engine works better with small rooms which connected with corridors or tunnels. Please remember that. Also you must think about players on public servers who may not have a good PC to render 20+ players in one room..