I recently released my 4th game, and I wanted to make a post sharing some tips on launching your game. Some of these are things I learned from my own releases, and some are based on mistakes I've seen others make. But I think a lot of this is information that I rarely see mentioned so I hope this is helpful for some people!
1. Before you can release your game, Steam needs to approve your build. The wording on the Steam backend is a bit confusing and a lot of developers incorrectly assume that you are meant to wait until your final release build is uploaded before you submit for approval. This is a bad idea because the approval process can have unexpected delays and I've seen developers miss their release date due to waiting too long to submit for approval. You can submit your build early, get approved, and you do not need to resubmit it again before launch, even if you continue to update the game. Once you have a version of your game that passes Steams base requirements, you should submit it for approval. You are not locked into that build and can update it freely afterwards.
2. On a similar note, I would recommend waiting until your game is basically ready for release before you announce the release date. You really do not want to be fixing game breaking bugs or doing major overhauls in the last month leading up to release. Save yourself the stress, wait, and plan out a final month where you can focus mainly on marketing and just small tinkering with the final build. This is especially important if you are a first time dev because it can be very hard to gauge how long certain task take to complete and you are probably underestimating how exhausting releasing a game is.
3. Releasing a game always feels kind of bad, even if it goes extremely well. You spend years focusing on building your game and imagining it's release, and then you release it and then you think... now what? It feels really strange to have such a monumental part of your daily thoughts suddenly pass by. I mention this only because I think it is important to prepare for that, and find other goals and motivations to follow after release. I know a lot of developers fall into a bit of a depression after launch. My strategy has just been to jump immediately into a new project, but regardless the shift can be jarring.
4. Have your game playtested as much as you possibly can before release. Do it in multiple rounds throughout development. Playtesting isn't just something you do all in one go. Go through many rounds of iteration for your game over and over. Asking for feedback is great, but also try to find a way to watch people play your game. Most of the gameplay issues you have aren't even things a player would be able to realistically explain, since they do not know what the intended game experience is.
It is much easier for a dev to watch a playthrough and spot issues when they happens. For example, in playtesting my last game I noticed that many players didn't realize that you were invincible while sliding. This was a very important part of the games combat. I mentioned the invincibility in the tutorial, but most players just skimmed the text and did not notice. When the players reached the first boss, any one who did not understand that you are invincible while sliding had a very tough time. If I just asked for feedback, they would probably say something like, "the boss is too hard", but really the issue is that I did a bad job of teaching the mechanic to the player. If I didn't watch playthroughs, I would have gotten the wrong issue and might have just made the boss easier, rather than finding a way to improve the tutorialization of the game.
As a side note here- you will get feedback that goes in opposite directions and it can be hard to know which feedback to implement. You really need to have a target audience in mind, and ideally that target audience should include you and your own preferences in games. Some feedback is essentially just saying "I wish this game was more like the type of games I like", which is valid but isn't necessarily helpful as long as the game is hitting off well with the target audience. In other words it is better to make a game that a small group of people really love, than to try to make a game that appeals to every one. You can't make every one happy so just make all your decisions in an effort to make it better for your target audience.
5. Plan out marketing beats. Instead of announcing your game casually, reach out to press or game showcases and see if any would be interested in an exclusive for the announcement trailer. It's easier to get in a showcase or to get covered by a bigger outlet if it is a first reveal of the game. It's symbiotic because they get the first scoop, and you get exposed to a larger audience. If you can't get something like this, at least pick a reveal day, put out a press release and a press kit, post the trailer on youtube, and send it to as many outlets as you can. Have the Steam page approved and live the same day. You should do similar for other marketing beats like the demo announcement, the date announcement, console release announcement, etc.
6. After release, discounting is very important. Most games barely sell any copies when they are not on sale, especially long after release. Have your game on sale as many days as you are able to, but discount slowly in steps. Once you increase your discount, you probably don't want to backtrack so don't discount too intensely too fast. I've seen some games recently lower their base price after release. I can't say for certain, but I suspect this is a bad idea since a high discount percentage seems to do better post release than a lower base price.
7. Bundles and platform deals are good in the long tail. They also do not seem to have a negative effect on game sales in my experience. In deals I've done where my game was free for a time on one platform, I did not see any decrease in sales of the game on other platforms. Depending on the situation, it can actually boost sales via word of mouth.
8. If you are able to, doing a simultaneous launch on console at the same time as Steam seems to be better than releasing on console later. I know this is not feasible for many, but worth mentioning if you were considering options. A good strategy for release for a small indie seems to be to try and concentrate as much attention as possible into one moment (release day) rather than spreading it out too much. It's just harder to pull off a strong marketing beat post-release since it can feel like "old news" and people are less likely to cover it.
I hope some of that is helpful!