It appears to be only using 90 degree corners. Like the
case above the player where the room to the right is dark,
and to the left it is bright, and the alien which is in the
middle is partly visible. Shouldn't the line be diagonal,
based on the location of the player? If not, what happens
if the player moves "up" a little bit, will the line stay
the same and then suddenly disappear, making the room to
the right visible as well? That would be a bit unrealistic.
It is more noticable for the small corner of the room the
player is in, on the right side, where the red object is;
this space should be entirely visible to the player, but
in the "area of sight" version, it seems to be completely
in the darkness.
Also the alien being only partly visible looks a bit
strange, like it is coming from under the floor.
So, summing up I think I would not use this system. Maybe
a better idea is to use a "line of sight" system so that
you can calculate more accurately which enemy is visible
and which is not.
Here's a "line of sight" function I wrote with a demo:
http://www.oprit.rug.nl/prins13/download/lineOfSight.zipAlthough when you use line of sight the downside of course
is that the rooms will still look the same (no darnkess).
I remember having seen games (both old games and BB games)
that do use this "area of sight" technique but in such a
way that the areas are formed in a more realistic way, even
if this means that you get "blocky" edges (since the
"resolution" of drawing these areas is the size of the
tiles). In fact you could use "line of sight" on the tiles
to get this effect... This is (was?) often done in RPG
games, typically those classic dungeon exploration games.
Then again, maybe the system you have there does work out
really well when you actually play the game, it could be
that the things I pointed out about the screenshots are not
really a problem when playing. And making the rooms bright
or dark does make it clear what you can and cannot see;
using "line of sight" on *only* the enemies has the big
disadvantage of the enemies popping out from nowhere.
(This is typically a problem in 2d games I guess; in 3d the
enemy would just be invisible since it is behind a wall; in
2d the area behind the wall *is* visible but the enemy is
not; your solution is to make that area dark)