Creatures Caves

I would add another dimension to the gameplay. I would make it what spore should have been, combined with the option of playing it as a sandbox like creatures. I apologize in advance for some serious tl;dr.

So, you start off in a fairly temperate biome with a certain number of norns you can customize. Customization will have consequences. Norns that blend in with the environment are less likely to be attacked by predators, grendels, or hostile tribes (more on that later). Norns that are brightly colored attract mates better. Every trait you could give your norns in the beginning would have at least one upside and one downside, as most real world traits do. For example, if you start out with highly intelligent creatures, they will likely be unhappy if you don't get them shelter and tools early on in the game, whereas more animalistic norns would be happy as long as they're fed, and sheltered during storms.

They interact with the local ecosystem. Without them (or any other creatures), the ecosystem could collapse. All creatures, including the norns themselves, would be diurnal, nocturnal or crepuscular. The environment would be a different place, depending on the time of day. Every plant and animal would evolve alongside the creatures. On this planet, there would be other ecosystems to explore. So, how does one preserve the former ecosystem while moving on to a new one?

You can separate your norns into packs, tribes, or nations (depending on intelligence and progress in the game). You choose a few norns you own, enough to support a population, and leave them as a separate group. New packs will not care about the split. However, tribes and nations, if not left with certain provisions, may get angry. Once out of your control, the packs/tribes/nations will continue to grow and evolve. Even if you leave on good terms, that might not last forever. You could even find yourself leaving behind a pack and coming to a powerful empire, bent on claiming your land.

Once a first split has been made, creatures begin to identify with their group. Depending on personality, some will feel more tied to it than others. You could have everything from a die-hard nationalist to a creature who hates the group to which it belongs, and wants to go to another.

At the beginning of the game, norn, ettin and grendel packs would be generated, as well as loners.You could add any of these to your creatures, regardless of species difference. Creatures could mate with outsiders, regardless of whether they're controllable or not. This would be a good way to help creatures adapt to a new environment, by mating with some of the locals. Creatures in tribes or nations might face consequences for doing so, however, depending on the culture. Mating with creatures substantially less intelligent would be a pretty big taboo. Once creatures are added to the group, they too develop identities (if the group yet has an identity). Groups with ettins and grendels will be more likely to independently develop tolerance.

An important aspect of the game would be the planet's resources. These would be used for everything from feeding your creatures to building death rays for them. Resources are necessary to keep the creatures alive. Some would be easily obtained, while others might be harder. Methods of obtaining them could be improved. Every resource could be obtained strictly by the hand (so your creatures who can't even figure out how to use tools could find themselves on a starship.), or by creatures who are intelligent enough and have sufficient technology to obtain them.

There would be a realistic weather system, that would effect the ecosystems.

Disasters, as many others mentioned, would be possible. The player would get a warning, and there would be an option to prevent a disaster. No player wants a disaster to wipe out their creatures who just survived a global pandemic. The disasters would be fairly realistic, only having earthquakes along fault lines, no tsunamis from nowhere, etc.

Creatures could make both technological and social progress, and the hand could greatly influence that (even whether it happens at all). The hand could avoid it altogether by making animalistic norns and not selectively breeding them for intelligence. In that case, the hand could still build things, but the creatures would not. For more intelligent creatures, the hand could order them not to build anything, though this could make them unhappy if the hand doesn't meet their needs. If allowed to, intelligent creatures will create their own technology and societies with the resources they can find. The hand can give orders to shape that, and build its own structures and items. So, the player is in the position to stop progress altogether or propell it forward, or even just sit back and watch.

Each creature, even the animalistic ones, would have a personality. There would be things they're good at, and things they're bad at. They would have different levels and concepts of altruism and empathy. Some would be emotional, while some would have the emotional capacity of a teaspoon. In tribes and onwards, this would lead to creatures developing roles. Their personality, skills and family history (in certain societies) would put them into certain roles, which they'd improve at over time. A creature could have infinite roles. However, the more roles a creature has, the more likely it'll have dangerous levels of stress or be unable to fulfill parts of its roles.

In the same vein, creatures would have agendas, often multiple ones, on a hierarchy scale. For a hungry creature, obtaining food would be high up there. For a miserable creature in a repressive society, freedom might be important, though perhaps not as important as self-preservation or the safety of her family. These agendas could shape society. Creatures with an agenda and a certain personality type may shake society to its core. The hand, of course, may support or end these efforts.

The creatures could get an opinion of the hand. At all levels, a hand who brings food will be more appreciated than a hand who beats up creatures for no particular reason. The hand's actions will be noticed, and creature's reactions would change accordingly. They could do as much as try to attack, act jealously to preferred creatures, or refuse to obey orders. Even so, the hand could take cruel or kind measures to resolve these tensions. Your creatures cannot kill you.

Eventually, the player could build a starship, and send the creatures into space. Space travel would, at first, be slow, taking generation. The hand could leave the ship in orbit, or visit nearby planets. These planets could be colonized, with the right technology. Unlike Spore, advanced aliens would be incredibly rare. Mostly, they would take the form of bacteria in water. The ship itself could be upgraded using materials from other planets, allowing it to move faster, grow larger, better simulate terrariums, etc. Eventually, the player might even run into the shee, or the Lone Shee, or even the elusive Banshee. There would be no endgame. The player could go on ad infinitum, even start all over again with a pack of animalistic norns on another planet, in the same universe, while their old group continues its development.

The technology and society could take many different forms (exponential, as compared to spore). Technologically, biological or mechanical technologies could be developed, or both could be used. Technology could have any or multiple focuses- improving daily life, doing research, exterminating enemies, making money, spying on the populace, or even just fun. Society could be as faceted as real ones are. There would be somewhat fluid ideals that developed as the group does, that the hand could influence. Society develops around these, and the actions of individual norns and groups of them. These would affect everything from mating procedures to leadership. Each society would be different this way, and affected by its history.

You could also choose only to control a smaller group of creatures within a pack/tribe/nation/general group of creatures without making a formal split. The greater group would continue to develop, though you could still keep unwanted changes from happening.

For the creation of a new game, the player could unlock new starting conditions as thee player progresses. Once you've built a spaceship? You could start a game on the spaceship. Added a grendel to your group? You can start with a group of grendels. Visited a desert? You can start on a desert planet or biome. Gotten amphibious or mer-creatures? You can start in a body of water, or on a water planet.

This would be a very versatile game that marries the biology, evolution lore and possibility for wolfling runs of creatures, the societal progress and interaction of spore, the individuality and independant progression of the Sims, and the resource obtaining aspect of games like mine craft. And, it's so complicated, there's almost no way a game like that it coming in my life time.