Thanks for the comment!
The upgrades have a % price increase each tier, and they are different depending on how many max tiers are there for the upgrade.
The counter = amount of undetonated dynamites, so for example, if 5 dynamites detonate together (a combo by closeness) the counter goes down 5 seconds
The dynamites are set 1 each second, but if you buy the "extra dynamite on jump" you will set +1 dynamite while jumping
Thanks for the feedback, I'll rebalance some things and increase the amount of info in the game to get rules more transparent!