I have this problem:
I quickly played right to level 11, or so, with in each level $4000 saved up. Everything was going smooth, and in level 12 I thought I should try to spend more money, and see what level 13 would be like with a tight budget. So I start level 13 with $1100, and it was impossible. It’s a level with place for 1 (one!) refinery, and that’s that. So I spend my first $100 on the refinery, and then I have $1000 left. The enemy was spawning right next to me, so needless to say, my 4 blasters were blown away. I didn’t stand a chance. And the game ended right there, there was no way to continue. Bummer.
So, my advice to you is plain and simple:
- allow the player to restart current level. (like you already do)
- allow the player to replay previous level. (to give them a chance to enter the current level with enough money)
On a sidenote:
Why not allow multiple research upgrades per level. If you have the money, why not? Because currently, if you skip an upgrade in 1 level, there is no way to catch up. Maybe this is simply a strategic factor, but I don’t like it too much If you skip upgrades in level 4 and 5, you pay the price in level… say, 100. That’s harsh!
Oh, and by the way:
that bottom bar is a major improvement