We consider the following combinatorial game (with two players 
alternatively playing optimally). Posititions are given by heaps containing $b\geq 0$ black and $w\geq 0$ white stones and are
encoded by $(b,w)$ in $\mathbb N^2$ where $\mathbb N=\lbrace 0,1,\ldots\rbrace$.

Players are allowed to remove either a unique black stone or
a set of two stones containing at least one white stone.
(Moves starting at $(b,w)$ correspond therefore to steps
in $\{(-1,0),(-1,-1),(0,-2)\rbrace$ which do not 
leave the first quadrant.)

Final positions with no move left are $(0,0)$ and $(0,1)$ 
and are either winning or losing independently (there are
therefore $4=2^2$ possibilities).

There seems to be no easy obvious pattern in the set of winning positions for these four games but my computer seems to be convinced of the following fact (for each possible game):

Fix $(\alpha,\beta)$ in $\mathbb N^2$ and consider for every 
$(a,b)$ in $\mathbb N^2$ the characteristic sequence $W_{(\alpha,\beta)}(a,b)$ in $\lbrace 0,1\rbrace^{\mathbb N}$ encoding 
winning positions in the arithmetic progression $(\alpha,\beta)+\mathbb N(a,b)$. All sequences $W_{(\alpha,\beta)}(a,b)$ are
seemingly periodic and moreover the union $\cup_{(a,b)\in\mathbb N^2}W_{(\alpha,\beta)}(a,b)$ of sequences
corresponding to all arithmetic progressions (with steps in $\mathbb N^2$) starting at $(\alpha,\beta)$ seems to be a finite (and generally fairly small) set.

*Should I throw away my computer?*