It depends on the casino and the bonus. Please be more specific regarding unlocking the deposit bonus, as you might unlock it and lose everything on the final bet, or if your looking to unlock it without losing anything, e.t.c. Assuming 96% RTP, you'd be expected to lose all your BTC before unlocking the bonus, and more.
If you play on DirectBet's casino, the best game for unlocking bonuses is Minesweeper. Pays 1 loyalty point per mBTC (slots give 2), and it has less variance since you can play with a low chance to lose (20% I believe)
It's very possible to get numbers. RTPs are given, all bonus terms are there, e.t.c