I think the sentence is wrong, it should either be "they had been playing football since 10 o'clock, meaning they started at ten and continued until a later time, or "they were playing football at ten" meaning at ten they were in the middle of the game. I think it is a mistake because the other sentences are all examples of the past perfect continuous.
Firstly, note that the best gift [that] I [have] ever have isn't a "sentence" - it's a "noun phrase" (within which the "head noun" is gift). Also note that it's perfect okay to include or omit either/both the "relativiser" that and the "auxiliary verb" have, and this has no effect on the meaning (it's entirely a stylistic choice).
BUT the second instance of have isn't an auxiliary. It's a normal verb usage, with the meaning get, obtain, acquire, receive,... So our choice is between...
1: This is the best gift I ever get
2: This is the best gift I ever got
3: This is the best gift I will ever get
In all those examples, the optional word ever provides emphasis (drawing attention to the fact that I never get or got or will get any gift better than this on any occasions whatsoever).
In most contexts, Past Tense (best I ever had) is the correct choice (in which case you're not necessarily ruling out the possibility of getting an even better gift in the future). You're saying that at no time in the past did you ever have anything better.
But note that Present Tense (best I ever have) doesn't exactly refer to present = now = time of speaking. It's the "timeless" use of the verb form, implying "never at all" (in the Past, Present, OR Future). And that's probably not the intended meaning.
It's possible to be even more emphatic by using could instead of will for the "future" reference in #3 above...
4: This is the best gift I could ever get
(there never was and never could be a better gift)
...and it's possible, though a bit clunky, to use that form for the "Past up until Present" context...
5: This is the best gift I could ever have got
(no past or current gift is better, but feasibly there might be a better future gift)
Best Answer
Here is one practical way to think of the difference between gift giving and giving gifts (when it's used after when it comes to as you mentioned in a comment, which is the focus of this question):
Which is why the two alternatives are quite possible if we generalize the patterns to [ X Ying ] vs. [ Ying X ], but one main difference is that in [ X Ying ] (i.e., gift giving), Y has become a noun, while in [ Ying X ] (i.e., giving gifts), Y is still a verb.
Having said that, I don't think there is a hard and fast rule that can tell which alternative is preferred. In other words, we have to select them on a case by case basis. (E.g., if a political leader is giving a speech after shaking hands with several other leaders, his saying When it comes to shaking hands, ... would most likely mean his shaking hands with other leaders, but when a doctor says When it comes to shaking hands, it could very well be about a medical condition. Also note that it has to compete with handshake, which is a well-known word, and probably is a better choice in your example.)
There are several terms for the two patterns (because there are several English grammars). But probably the most well-known ones for the two are: