It's a bit more complicated than just aiming for a win percentage. We can build bots you'd never beat that hold a 50% win rating. We actually did this early on. The bots are much more dynamic now and we can keep tweaking and adjusting them over time. Originally we had nothing between "free win" and "instant loss" and now there's much more granularity. There's some difficulty in catering to players with drastically different skill levels as well, so after 3700 you're basically always playing the hardest bots, we put some restrictions so you aren't just playing heloise bots every time, but it's ultimately a balancing act. What's easy to you may be hard to someone else and if you can beat a bot every time and I lose to it every time, that's still a 50% win rate. All in all, it's more complicated and complex than just aiming for a number. Bots should be adapting over time to become harder or softer based on rating. Just submit the feedback and we'll compare results/notes and make adjustments where we can.