1. Height
2. Light/Shadow
3. Textures
4. Detail
5. Flow
6. Variation
I will now explain each one.
Height. No real place is flat. Look out the window. The grass is bumpy, or the row of houses
goes uphill, or the paving stones are unequal heights. This constant variation should be
reflected in the height of your terrain, or the layout of your city. Also, height of
buildings matter, as not many buildings share the exact same height, so variation is
important. Also scale is important, as the right scale, will create a better sence of reality.
Light/Shadow. The light settings are important, and also that they match the selected sky,
and atmostphere of the map. Ambientlight should always be kept low enough that shadows can
be seen fully, Never, ever use over 20 20 20 - this will make for an unreal, plastciy looking map. The real light source
you should use fully is suncolor, as this will create nice directional shadows, and you
can place the sun as to where the shadows will create most impact. Sunlight is useful for moonlight too - change the colour of it. Do not rely on
ambientlight for the rooms, and have an individual light entity, with a lamp model to make
it look more real. Variance in colour of light entities can also add a great effect.
Textures. Getting the right textures for your map is important, and can be done by roaming
around with a digital camera, or searching on the web. Getting a theme going is what the
textures do best, and should be all kept to thet theme, whilst still varying, to keep people
interested in the textures. Scaling of textures is even more important, as if a chalkboard
is the size of a house, it kind of ruins it. Also some textures do not collate, so need to
be fitted to the brush. Here again, scale is important. It is good to keep the theme flowing
and try to avoid too many real oddities, as it can destroy the image completely.
Detail. Detail is what will keep someone interested, so go and add varied things you see in
everyday life, like drains, pipes, taps, vents, anything that fits in with the theme, but be
careful not to go overboard, as it tends to overcrowd the map, and makes it feel cluttered.
Detail is also important on textures, and will help to keep people interested, and make it
seem like a more realistic environment.
Flow. It helps to be consitent in your mapping. This does not mean sacrificing variety. If your map has a certain 'flow', keep that going throughout the whole map, otherwise it may spoil the feel of a good map. Flow goes for details also, too many details can clutter the map, and it becomes unatural. Also try to keep textural oddities down to a minimum. Whilst one or two are good for creating a more authentic atmostphere, too many can ruin the flow of the theme.
Variance. This is the real keystone, and the word (or one of its variants) is infact used in
in each of the above paragraphs. Varied height, colour, texture, light, detail and angle is
what keeps people interested, and will keep the person looking. Variance is real, look out
the window. Each tree is different, the houses are different sizes, even the colour of your
wall varies as you look at it. This, you should try and reflect in your map, by varying as
much as possible. Also people want not only new maps, but fresh ideas to play with, new
scenarios and new game types. Try to be inventive - there are hundreds of maps that people
can download that may be good, but don't really offer any new concepts. There are no standards
to how a map should be played, so let your imagination run away and create something really
original and new.
How do we know this?
Take a look at your first map. No doubt you now think it rubbish, and
should do. What makes it rubbish? It probably only keeps to one of the points, in a few cases
more, but most around 1. It has out of scale stretched textures, it has a weak light entity,
or high ambintlight, which go to make it look plasticy and unreal, it has no detail, and it
has unvaried right angled corners. So if that is a bad map, it is obvious to see that a good
map is the opposite.
You may be shouting 'gameplay' but since there is no real formula for gameplay, and there are so many variables, that it is almost impossible for one to tell another how it is done. We can dispense a few tips though:
O, U and 8 shaped maps (as basic layout) are ideal for larger maps, with cover and ambush points being frequent, and try and avoid to many open spaces. You need to get the right balance - if the map is OBJ you need an equal amount of hiding places, cover and open landscape for both teams to make it fair - otherwise people will just want to go on the good team, thus destroying playability. If your map is DM, make the whole map consitent in the number of cover/hiding places, or good places for a shootout. Otherwise people will end up playing only half of your map. For SP, make sure it is a challenge but not impossible. A 'medium' difficulty level would be the best level to aim at.
Whilst you have those shouting 'gameplay', you have those screaming 'FPS'. A difficult topic if you want a real good looking map, but it
is possible to keep FPS up, by utilising Vis leafgroups, and the like, which, isn't really my area our expertise.
Mj + m4rine
Apologies, I just felt like digging this up, reading it, then doing a little editing
I know that Bjarne, but this is specific to making the map look good, rather than making a popular map, or a playable map 
