http://www.newgrounds.com/portal/view/578726

Tower have no cost:
96 07 00 08 a2 07 64 00 00 00
96 07 00 08 a2 07 00 00 00 00

Tower upgrades have no cost
96 20 00 08 ab 07 5c 12 00 00 07 fc 08 00 00 07 4c 04 00 00 07 f4 01 00 00 07 2c 01 00 00 07 05 00 00 00
96 20 00 08 ab 07 00 00 00 00 07 00 00 00 00 07 00 00 00 00 07 00 00 00 00 07 00 00 00 00 07 00 00 00 00

Gems have no cost
96 20 00 08 aa 07 c8 00 00 00 07 c8 00 00 00 07 c8 00 00 00 07 c8 00 00 00 07 c8 00 00 00 07 05 00 00 00
96 20 00 08 ab 07 00 00 00 00 07 00 00 00 00 07 00 00 00 00 07 00 00 00 00 07 00 00 00 00 07 00 00 00 00

EDIT
Enemy dies when it comes onscreen (change all)
96 04 00 04 02 08 8c 4e 96 09 00 06 00 00 00 00 00 00 00 00 67
96 04 00 04 02 08 8c 4e 96 09 00 06 00 00 00 00 00 00 00 00 48

Score is *8 4Bytes, adress changes, so get to high score, pause, search, change, wait

EDIT 2:
How to easily get maps won medals
Change sol to get 1 gold medal
This changes medal awarded from 1 gold medal to map of your choice (from 01 to 0a for ??)
96 0c 00 07 0b 00 00 00 07 01 00 00 00 08 27
96 0c 00 07 ?? 00 00 00 07 01 00 00 00 08 27

This changes which map you will get medal for (change ?? to same number as above)
96 03 00 09 15 01 1C 96 08 00 07 01 00 00 00 09 30 01
96 03 00 09 ?? 00 1C 96 08 00 07 01 00 00 00 09 30 01

Run game to make stuff happen (broken image removed)