The game is definitely large, that's just a result of the rooms all being equal size (except shops) and generated as you open doors. The more doors your open, the more space is filled, thus the larger the world seems. This is entirely controlled by the player in that doors do not open without interaction and rooms don't generate until the instant a door is opened.
As for concerns about game play, there is currently no goal. There is no back story or win/lose condition since I didn't have time for those prior to submission, though I do want to add them in the future. Automatic coin collection was deliberately cut since the coins are a major trade-off, so it felt like it would punish the player for not avoiding them rather than punish them for hoarding them as I envisioned. Auto-exploration/fast travel were likewise not included because the game was about the player balancing their choices according to their situation. Do you continue along the same path in hopes of a new store nearby or turn back to one you know exists? Do you carry the coins and waste your time trudging slowly through many rooms, or press on knowing you can come back for them later? Adding ways to essentially bypass these choices means the player is less a player and more an audience. Though providing the user a one-way "fast recall" to the starting room via a one use item could be a reasonable future addition
The rooms are randomly generated, with various chances of containing things like coins, targets, shops, challenge doors, etc. A challenge door (door going up from main path) will lead to a path of variable length with higher chances to include rooms with more coins or challenges to overcome, but still has the chance for a room to be empty and/or a dead end. The rates of things being included likely needs tweaking in the future, but part of the issue again falls back to things that I had to cut for time.
A bug with movement throwing you off center was something I rarely experienced in testing and development (would sometimes inconsistently occur with coins in front of doors), if you could post an issue report on the github on how to reproduce that (if possible) I would very much appreciate it @zinkler