What Iâve generally noticed of âlow polyâ is that there really is no style thatâs plainly referred to as âHigh Polyâ, and by that I mean, thereâs not a universal number of faces that changes the style. However, using sculpt mode to build something rarely ever results in something that is low poly, and tools like ZBrush can create really smooth and detailed characters that often results in a high vert count.
After all, 1000 triâs might be a small number for a character, but a large number for a weapon or piece of clothing. You have to look at exactly what youâre trying to model, and think of how few vertices you can build it in. Thereâs no real âreference sheetâ of how many verts things should be, just experience and practice.
The typical rule for low poly:
1: Stick to block modeling. You may be tempted to use sculpt mode; and using it for subtle movements is fine, but using it to draw on your model will quickly overload your vert count!
2: Donât add a whole loop cut around an object if you only need one vert out of place (like, for an ankle!) Cleverly cut and build your model so that you only end up using one extra vert, and make sure it doesnât result in an Ngon.
3: Donât use geometry to add detail unless necessary. Your character might need a belt, say, but if itâs too intricate or doesnât need to move around at all, you might as well make it part of the texture! With normal mapping, you can simulate depth, so you donât need real depth. Good texture work makes all the difference; something that seems super advanced might only be 300 verts! Great low poly characters can go sub 1000, but perhaps thatâs a few too few for Second Life.
Low poly is about being vert-economic! I tend to get sloppy when Iâm rushing, and add in say, 4 loop cuts to make the walls for a room, but if you didnât need that much complexity, you could get away with a single inset.
EXAMPLE TIME
A leg has key geometry: The hip, the thigh, the knee, the lower leg, the ankle. Technically, for the lowest of low poly models, you only need 1 loop per each of the key parts. The leg itself only needs to be rounded in shape, so it could be anywhere between 6 and 12 verts around (x5 for the key loop cuts, so about 30 to 60 verts for the WHOLE leg!)
HOWEVER, the knee requires more geometry if you intended a character to walk. Refer to what I said about âOnly use as many verts as you needâ. In my experience, I split the verts along the front of the leg to create the knee. (Using v, you can tear one vert into 2)
Now we have a leg thatâs under 100 verts and will bend well when animated. Youâre not going to get flowing flesh or rounded calfs, but for low poly, itâs all you need.
Actually, it looks like maybe Marvelous Designer was used in making Assasinâs Creed. Here is an interview from one of the artists plus there are several more short ones for other games and such. 
