I have a few gameplay things I've been noting as I play the alpha that I thought I'd post. Of course they aren't very urgent but I thought they might helpful to think about when working on the gameplay and visuals more down the line.
!) It would be nice if there was some way for players to better adapt to different surfaces, especially in the amount of spin they use. I could see this working well with a skill, maybe that can have one or two stars in it. If a player has this skill their spin will automatically adjust for different surfaces. This would better simulate players like Nadal and Thiem who flatten their strokes out a lot on hard and grass courts.
2) I know you have already tweaked this a bit (and I think this is probably pretty subjective), but it still feels to me like slices are overpowered, especially with the slice mastery skill. When playing with 2 points in slice mastery, the trajectory is incredibly low on every slice, and often the shot has an unrealistic amount of pace. Perhaps rather than make the shot stay so low or give it more pace, the slice mastery skill could make it stay consistency deep and give it more spin? I feel like that may more so be the strengths of players who do actually have the best slices.
3) Have you considered increasing the left/right adjustment of the camera view editor? It would nice to be able to set a court-side view to watch point replays with, but the side-to-side slider doesn't go very far at the moment.
4) One small thing that I've noticed is that though different people in the crowd start clapping at slightly different times, they all stop clapping at the exact same moment. Maybe you could adjust this so that there is a little more variance in when they stop clapping so it doesn't look so abrupt.
5) One thing that looks a bit odd is that the players head always follows the ball, which usually makes sense, but looks weird at times. For instance, pros don't usually track the ball when returning serve and the serve goes out. Once it passes them they are looking forward getting ready for the second serve. This also looks on in doubles when the player at the next is staring at their partner who is about to serve, when they should be looking towards the player who will return the ball.
6) Finally, I think it would be nice to have back buttons on each screen when setting up a new World Tour game. At the moment when you select a player you can't go back to the full list of existing players, which is frustrating because its very easy to click on the wrong one.
I don't mean to be overly critical with all these thoughts, I just been playing the alpha a lot and have noticed some of these over time. The game is coming along so well, and you should be proud of the incredible product you are making! I know you get many comments of people asking about release date and when the game comes to console, but I am just amazed that you are making as much progress as you are working on it all by yourself. And unlike most developers, you are very responsive to the game's community, which is what makes Tennis Elbow such a great experience. Keep up the good work--we are excited to see what's in store for TE4 in the future!