The possibilities for tampering are endless! - Here are some suggestions:
Hops: Add optional hops for extra aroma
Sourcing: Use Philly Sour yeast
Low carb: Add Amigase for full fermentation
Gluten reduced: Add Brewer's Clarex
Increased strength: Omit the water, or add extra fermentable sugar (malt extract etc.)
Lactose: Give the beer an extra smooth body and sweetness
Other additions: Oak, coffee, spices, orange peel, fruit/puree, cocoa nibs...
Suggestions for hops and yeast:
As mentioned, we want to encourage experimentation. Nevertheless, it can be good and reassuring to have some concrete suggestions, which can also inspire you to make your own adjustments. Here are some suggestions:
FWK Creative also works great for using up leftover hops!
Feel free to read about what aroma each hop contributes, and choose what sounds good together - This is fun, and you are often impressed by new hop combinations!
General recommendation for carbonation:
Add 6g sugar per liter of beer when bottling, and let it carbonate at 20-28°C for about 14 days before storing in a cool place.
CO2 volume in keg: about 2.5