I downloaded this a few days ago and have been playing during my commute, and I'm enjoying it.
In terms of progression/motivation, getting a high score wasn't particularly motivating, in that it didn't tie into anything else I was doing. (The same way we don't pay attention to the score in old Mario games, because the addition of an end state made the score irrelevant.) On the other hand, I found getting to the oil compelling, but too easy until about level 20.
I think the following structure would be worth a try:
- Rather than have rarer letters be worth more points, have them represent ores that you can use to upgrade your drill. (Like, allowing five iron ores to upgrade the drill by one durability point, giving you one more turn on subsequent plays.) That gives you some in-game motivation to utilize rare letters.
- Have levels be pretty long, such that you're unlikely to get to the bottom on your first try with an un-upgraded drill.
Since collecting ores is progress, it won't feel like such a sting to not-reach-the-oil; you're not "failing", you're just in-progress towards success. But then when you DO finally reach the oil, it'll be more satisfying, because it took some luck, some work, and some word-smarts. (Meanwhile, allowing drill upgrades means that less skilled players can, through hard work, still beat difficult levels eventually.)
I agree with Uncle Scotty that doing level select as a "map" of wells would be a nice touch. (And with long levels that players attempt many times, it would mean you may only need four or five wells total.)
Some minor points:
- Diamonds were a little too easy to collect; as play went on I usually found my remaining turns rising rather than falling, giving me little feeling of pressure. It might be worth a try to only allow the player to pick up a diamond when making longer words.
- My drill would sometimes make bad decisions about which way to go, and get stuck on rocks. This wasn't really a fun kind of failure; I would rather just drill and not have to worry about what decisions the drill AI is going to make.
- My level unlock somehow got ahead of my play, so that every success unlocked the level two levels ahead of what I was playing.
- For visual clarity, it might be worth indicating wildcards somehow (like with an asterisk or question mark). Having nothing meant that I kept getting having little moments of confusion between diamonds and blanks (thinking that diamonds, being blank, will give me a wildcard letter, or that blanks, being blank like diamonds, wouldn't count).
Anyway, good work; I'm following with interest!