Cross Edge, Trinity Universe , Legacy of Kain Defiance...ect why not..

[Severance]

Uncharted x Tomb Raider , Lara tries to steal a treasure, but soon finding out another person trying to get it first and that person is Drake

Jak x Ratchet , Ratchet lands on an unknown planet, having his ship crashed, he can't get it to fly again, but Jak founds out that he can help him using the "Precursor Crap" <-- anyone gets this is a true Jak fan

Devil May Cry x Bayonetta , Dante gets called to take out a witch .... yeah , you know what happens

 

so what you guys think more cross overs should be?