World creation:
Wandering hordes are nice.
Random NPC spawns are nice.
Misc:
Automated turrets and weapon platforms are extremely dangerous. They usually have superior night vision and are placed in dark secure areas or around the corners of places you shouldn't be. Use Shift + X or Caps Lock + X to peek around corners. If certain weapon systems spot you for the first time, you typically have 1–2 "turns" to move out of its line of sight. If you're too slow, it can kill you instantly. IMMEDIATE evasion, clever manipulation of the environment, or indirect attacks are the only way to competenly deal with these. The turrets and weapon platforms commonly kill late-game OP characters without immediate solutions to electronic gun-mounting enemies.
NPCs with firearms are also highly dangerous and difficult to duel, depending on your speed, dexterity, and perception relative to their own.
Traps are invisible to the player. You can only discover a trap’s location by keeping the tile it occupies within your line of sight, with the required time depending on your Perception stat. Some traps are easier to detect than others.
Certain late-game items and locations can only be accessed with ID cards (found on corpses or certain locations or brute-force: such as mining equipment, tunneling tools, explosives, or hacking devices.
Some zombies are best dealt with using firearms at range; others are better handled in melee. Some types require heavy armor-piercing ammunition or piercing weapons to kill effectively. Certain zombies regenerate quickly.
Certain armors often cause encumbrance, resulting in diminishing returns during melee combat. Most martial arts thrive on low encumbrance due to their use of dodge chances and action speed spam.
Monsters evolve to make the game harder. Parisheble food expires.
Pressing "@" and tabbing between the displays allows you to see your character's disposition. Warmth and encumberance are shown, top, second panel. Certain vehicles, weather (seen in the map by pressing w), or seasons require you to keep better track of your warmth stats. Certain martial arts and melee requires you to keep track of your encumberance. If you're visiting a place you suspect to be irradiated, checking this from time to time and looking at the "effects" tab is a good idea.
Your scent radiates outwards from you and lingers. Others can smell you.
Certain monsters have special behaviours, capabilities, or problem solving abilities.
You can use a hose, or anything with the "siphoning" quality, to drain fuel from one car in order to move it to another or a container. You can smash a fridge with anything sturdy to acquire a hose.
Using "shift+x" or "caps+x" and > or < allows you to see above and beneath you. Monsters and NPCs can also see above and below. Monsters may reach, grab, pull you towards them, or attack you from a different Z-level if you're too close. Low flying in a helicopter with a semi-open cockpit may prove lethal if something grabs you or attacks you! Certain enemies can IMMEDIATELY take down a helicopter if they fly into its rotors!
Sure do hope those zombies don't evolve to fly or anything...
Going to an elevated place allows you to see further, filling out your map; wearing binoculars helps you fill out your map at a wider range.
If the game spazzes out and buries you inside the ground for no reason, use the debug menu to teleport to where you were.
"/" or "\" allow you to haul items or better sort them. Contextual button prompts allow you to search or better sort these depending on category in case you have a massive pile of items.
If transferring items between two spaces with "/", the trunks of cars are noted by name and shown as "v" in the radial menu.
Dying is fun!