Imagine having not only random creatures and groups of enemies, but also different actual races that can establish themselves on your map, to interact with both yourself and other races/species in the world making for some really unique and ongoing situations and events. It’d make for some great and varied gameplay and for some awesome stories the likes of Dwarf Fortress create, to remember and to share with friends for a long time to come.
I’ll make a few examples of the types of races/interactions/situations/events that could be awesome, to happen. A few races for the example(s): human, undead, orcs, lizardmen, goblins.
First, each race could have different default affinitys for other races/human factions (with chances at being somewhat better or worse) for example humans generally like and are friendly with other humans, undead hates everything else, orcs and goblins generally like eachother and will ally and fight together while lizardmen are docile and reptilians and so are neutral until you enter their territory or otherwise upset them.
As well as unique affinitys toward other races, each race could also have unique combat strategies, units, abilities both in and out of combat, traits, attributes and anything else that is viable to be made.
Humans: Would be a relatively traditional/standard setup - also able employ the mmo holy trinity of tank/dps/heal of course and enter the map with random gear for each unit in each role. generally medium life medium damage with tanky melee, ranged damage and heals. They could have the ability to build ladders on walls and mountains nullifying your safe and easy invulnerable defences especially when building up against a mountain, etc so there is no situation where you will never be touched again. They can potentially ally with other humans also. You can trade and generally communicate with other humans that are established on your map, that you are friendly enough with. You may be able to ally with friendly factions to help fight enemies. They tend to also build a kind of base with walls maybe a few random traps around the outside, and a few random small building to act as barracks, main base, ramps leading up to walls for archers to guard on etc. A cool looking traditional base style setup. Medium threat.
Undead: Combat strategy could be to swarm, while resurrecting everything that dies along the way (that isnt already undead) to build the size of the army. Maybe they usually try to kill things that are in smaller numbers first for added advantage and to then resurrect to grow their size, so they may roam around the map at first killing off random creatures, races, travellers, stragglers etc. Could have a necromancer as the leader/boss unit that does the resurrecting and also sets up a graveyard or a crypt in a mountainside, once it has a big enough army and doesnt need to do the roam recruiting itself, as a base that kind of spreads corruption around it, slowing all other units on it while giving its own units a bit of speed and health regen and maybe some other cool effects. Maybe undead units are generally slightly weaker from being undead and using swarm tactics but are resistant to bow/arrow damage and/or certain melee weapons. (good ol swords/slashing but are weaker against hammers/maces/crushing) Will never be friendly with anything and wont trade/communicate with anything. Low threat initially but risky to leave alone becoming high threat after a time.
Orcs: Very tanky mofo’s with high damage also but are mostly melee, dont have healers and just throw their strongest warriors at you though there aren’t usually “too” many in numbers, each wave to compensate. Can break through base walls. Can tame wild creatures to fight alongside them or guard their encampment. May team up with goblins to pose a bigger threat. Will want to clear most other races out and claim the map for their own so are always aggressive, always attacking someones base when they have built their own encampment big enough and have extra units to send out. medium threat with potential for high threat if ally with goblins.
Goblins: Weaker than usual, more numbers, mostly ranged: goblin stone slingers, archers, javelin throwers etc as well as goblin shamans for healing and hopefully some day magic dps. Usually more of a threat if there is any orcs to team up with around the place. Will try to kite with ranged units while in combat while separating and generally skirmishing you which can wear you down and be pretty dangerous. Will usually build in mountainsides or underground. Can dig holes into your encampment and/or come up anywhere from the ground in general. Can lay stealth or bush/forest ambushes with groups of goblins outside of bases or anywhere else of potential interest. medium threat with potential for high if ally with orcs.
Lizardmen: High amounts of life and armor due to rough lizard skin and equipment but lower damage using claws and daggers, or trying to wield a select few weapons more suited to humans like spears etc. Lizardmen could use poison from their claws that they also put on weapons to have chances at applying poison, that does maybe low damage also, but is long lasting and slows units. Even though tanky and lower damage there would generally be bigger groups/numbers of lizardmen being reptilian and breeding more than usual. Both melee and ranged but no magical/healers. Generally neutral until something else enters their territory before turning violent and becoming enemies and aggressive with you from then on. mostly build/settle around water so even though they initially wont come after you, you may still need to deal with them to have access to water and/or other important resources around the area. Can swim in water and potentially enter your base through water systems. Has a permanent low chance of turning hostile and aggressing upon you instead, so you are never completely safe from them if you dont go near them, as they may want resources or something in your area. also have to watch where their units go, to make sure your paths never cross making them turn aggressive.
Now, imagine for example your playing on a map and a human faction moves into the area and starts building up. You try communicate with them but they don’t want to ally and/or become friendly. Before long they send out an attack party and climb down your mountainside and are in your base and start attacking your population and a crazy fight breaks out.
Sometime later, while still fighting with the humans, a necromancer boss randomly enters the map and starts roaming and killing creatures, stragglers and random travellers going from one edge of the map to the other (who you can also trade with or attack for their stuff as bandits, but damaging your rep with their faction who may retaliate and who could even become another human settlement…) building up an army while you fight the human encampment while also resurrecting any casualties from that war.
The undead start growing pretty big and you start to worry so you communicate with the humans again, giving them a ton of free stuff and gold enough to become friendly and/or maybe even ally. either way you can then turn your attentions toward the undead base whether the other human faction joins in or not, knowing they at least wont attack you for now.
At some stage during the war with the undead, while scrolling along the map you see an encampment of lizardmen over by the lake and make a mental note to not go near them. The fight with the undead encampment isnt going so well until the other humans decide to join in, making it a big crazy 2v1 war with the undead but before long you get a message showing lizardmen are attacking you and you realize one of your guys went to go get water and crossed their path and so you are now at war with them and fighting a war on 2 fronts.
Now imagine if orcs and/or goblins and/or other factions etc came in, imagine how you would all uniquely react with eachother both in and out of combat. I can guarantee there would be some awesome and funny situations haha. Most importantly some unique situations making the replayability amazing.
TL:DR More stuff going on in the world to interact with for better or worse ftw. Other, unique, races with unique reactions and interactions to the rest of the races and world both in and out of combat, ftw.