[kow75]

This would be something built into the server as a plugin. No one can pick them but admins can adjust the affects in a cfg file or using cvars.

They randomly spawn in the server and fly around doing damage to who ever they find.

Example:
Super storm on a map like de_aztec the thunder sound makes lightning strike and hit random players doing x amount of damage or strikes random spots in the map.

On dust maps a dust storm comes in randomly and blows the skin off of all players out side of the tunnels doing x damage.
if a player learns "sand cloth" the storm wont kill them as fast.

On glass maps and earthquake cusses some parts of the map to shatter. On other maps it brakes all breakable entities and makes the lights in the map fade in and out. In some cases will turn off the lights completely.

A tornado/hurricane causes source phys_props to blow around if they hit a player at x speed it does x damage.
For 1.6 the tornado/hurricane causes the player to be picked up and thrown across the map.
For the hurricane it can cause maps to flood.

Flash Flood: It starts to rain hard out of know where on maps with rain. Then water starts to flood the map extremely fast.
Any one caught in the rush of water will drowned instantly. Unless a player learns "swim training"

Volcano: Maps with large displacements. A volcanic eruption takes place for all to see. then it rains ash just before it explodes. Then lava balls start falling like hard rain burning players. Some players will catch on fire and die.

Asteroids and Meteorites: On maps with the night skybox
You start to see a pretty meteor shower in the sky. Then chunks of all sized start to impact the map.
Small pieces do minimal damage but large pieces can do extreme damage even as much as killing a player.

Bermuda:
different parts of a map are designated disappear points.
This is where a player turns invisible while in that spot.
OR
While playing players and random props disappear from the map.
Wait an amount of time then re-spawn back into the map.

Ice Storm on maps like cs_office and iceworld "snow maps" could work with others.
It rains ice, when it hits the ground it makes large puddles of water that instantly freeze into frozen ice.
If a player is caught in the storm (out side) it causes them to freeze and be like a statue.
When the storm is over the players out side that got caught defrost.

and any thing else you could think of for this type of Environmental plugin.

All these will need timers of reaction. To specify how long to wait once a new map is loaded. Also a cool down timer before it starts again.
Some environments need a variable to only react to specific things in a map. Example sky_name, rain_entities and func_water.
While most of the environments only work for special map names.

[Voi]

wow u have nice imagination, but...

and as i know phys_props are "source" thingies, hl doesnt have them

[kow75]

Sorry you read it wrong. Easy mistake, because the sentence runs on.
"they" in that sentence meaning: (The tornado/hurricane) not the props.

I was giving an example of what the environment damage would be like in EACH engine. Labeling the affects as what each engine can Handel.

If you read it again it said for (source) it can to this but, for (1.6) would do this.

But all fix the they to clerafy