If I'm playing on the lowest difficulty and there's no snowballing, what does gameplay feel like? What feedback would I get from the game that it's time to increase the difficulty level?
Let's separate the default difficulty from the lowest difficulty. The lowest difficulty is usually even easier than the default one, and I don't think many people play it. I believe game designers made the default difficulty the most comfortable landing for the majority of new players to improve their onboarding. From this point forward, I'll be talking about the default difficulty.
The default difficulty achieves 2 things:
- It lets players explore the game and try different portions of it without falling too much behind their opponents
- It creates just enough challenge that people have fun overcoming during their 1st playthrough
Which means, the default difficulty should be a compromise on different aspects, for example:
- AI should not be very aggressive, but it still needs to settle and expand, so that the world feels alive.
- AI may not have the most advanced units, but it still needs to build an army and invade the player at some point to create interactive situations.
- AI should produce yields that aren't too high or too low, so that the player doesn't feel hopeless or even stupid. Ideally the difficulty should be adaptive, but it's difficult to tune and get right.
The difficulty setting also affects the behavior of certain gameplay systems. In Civ 2, the lower your difficulty was, the less demanding it was for players to keep citizens happy. In Civ 6 or Civ 7, the AI gets combat strength bonus, which requires players to do more preparation than they would've needed for "fair" battle. It's not a bad thing per se, but it should be used very carefully and sporadically. I think Civ 6 goes absolutely nuts with bonuses it gives to AI on higher difficulties and it hurts the experience; higher difficulty doesn't make the game more interesting, because the AI remains a pushover. But it does make the game annoying, because you get to miss a lot of early great people, settlement locations, or even become attacked by a number of warriors with a significant combat bonus on top.
When the player finally overwhelms AIs on the default difficulty, higher difficulty levels start offering a degree of replayablitity due to increased challenge. It's where players can use all gameplay skills they earned previously, find and overcome new challenging situations and meet new opportunities to learn more about the game. For some people, the approximate maximum on the learning curve is essentially the depth of the game (I don't agree with this, but the logic is understandable). The "snowballing" aspect is the result of using all combined knowledge about the game to achieve new degree of empire "greatness" and feel accomplishment from your results. I think different gameplay achievements offer different degrees of snowballing, and as the player goes along, more hidden synergies become obvious, more mechanic interactions are memorized, and from all of those new snowballing strategies emerge. I think it's quite similar to how people create meta decks within CCGs: through trial and error, experiments and analysis (CCGs don't take as much time to master though, but they often have frequent card drops to keep the loop fresh).
Overall, snowballing is a reward for learning the game and using this knowledge to its best during the playthrough, and good game design makes snowballing reasonably hard to make the achievement rewarding.
Can snowballing be removed from the game without the cure being worse than the disease?
No. Snowballing should not be removed from the game. It's not a disease. Removing snowballing will create a pure spreadsheet simulator, which (I assume) is very different from what Civ audience wants. Instead, there should be different degrees of snowballing, each with its own skill requirement and rewards, for all kinds of players.
Part of the problem is that for different people snowballing means different things. This depends on the skill level and the informity about the game. For some people, abusing Magnus chops and high adjacencies creates enough yields and tempo to call it snowballing. For others, suzeraining Kumasi and sending traders create culture amounts resulting in snowballing. But there are people who think of those as just regular gameplay stuff, and to them snowballing means achieving even greater heights, even more unstoppable avalanches, by using all their opportunities to their fullest and balancing around different gameplay systems.
I think Civ 7 failed snowballing for the 1st kind of players (more casual and chill), but it still provides enough of it for those who seek high-level gameplay and competition. There isn't enough satisfactory moments that can be achieved without very deep game knowledge and situational awareness. So the majority of people feel like there isn't any snowballing to their gameplay, or rather, there isn't any greatness to their empires or any meaning to their achievements. And I'm not blaming them; if the game aims towards casual players, the development team needs to keep them in mind when designing and tweaking gameplay systems. I feel like there wasn't enough playtesting by different cohorts of players before release, and a lot of systems were tweaked based on feedback of designers playing against each other. Game designers can pinpoint objective issues in systems they create, but it might be very hard for them to envision how their game is going to be experienced by different kinds of players.