diff --git a/source/engine/anim.c b/source/engine/anim.c
new file mode 100644
index 0000000..dfb2fb8
--- /dev/null
+++ b/source/engine/anim.c
@@ -0,0 +1,54 @@
+#include "anim.h"
+#include "stb_ds.h"
+#include "log.h"
+
+struct anim make_anim() {
+    struct anim a = {0};
+    a.interp = 1;
+
+    return a;
+}
+
+struct anim anim_add_keyframe(struct anim a, struct keyframe key) {
+    arrput(a.frames, key);
+
+    return a;
+}
+
+double interval(struct keyframe a, struct keyframe b, double t) {
+    return (t - a.time) / (b.time - a.time);
+}
+
+double near_val(struct anim anim, double t) {
+    for (int i = 0; i < arrlen(anim.frames) - 1; i++) {
+
+        if (t > anim.frames[i+1].time)
+            continue;
+
+        return (interval(anim.frames[i], anim.frames[i+1], t) >= 0.5f ? anim.frames[i+1].val : anim.frames[i].val);
+    }
+}
+
+double lerp_val(struct anim anim, double t) {
+
+    for (int i = 0; i < arrlen(anim.frames) - 1; i++) {
+        if (t > anim.frames[i+1].time)
+            continue;
+
+        double intv = interval(anim.frames[i], anim.frames[i+1], t);
+        return ((1 - intv) * anim.frames[i].val) + (intv * anim.frames[i+1].val);
+    }
+
+    return arrlast(anim.frames).val;
+}
+
+double cubic_val(struct anim anim, double t) {
+
+}
+
+double anim_val(struct anim anim, double t) {
+    if (anim.interp == 0)
+        return near_val(anim, t);
+
+    return lerp_val(anim, t);
+}
\ No newline at end of file
diff --git a/source/engine/anim.h b/source/engine/anim.h
new file mode 100644
index 0000000..358dfba
--- /dev/null
+++ b/source/engine/anim.h
@@ -0,0 +1,20 @@
+#ifndef ANIM_H
+#define ANIM_H
+
+struct keyframe {
+    double time;
+    double val;
+};
+
+struct anim {
+    struct keyframe *frames;
+    int loop;
+    int interp;
+};
+
+struct anim make_anim();
+struct anim anim_add_keyframe(struct anim a, struct keyframe f);
+double anim_val(struct anim anim, double t);
+
+
+#endif
\ No newline at end of file
diff --git a/source/engine/mrbffi.c b/source/engine/mrbffi.c
index 524fa10..bb51e98 100644
--- a/source/engine/mrbffi.c
+++ b/source/engine/mrbffi.c
@@ -14,6 +14,7 @@
 #include "openglrender.h"
 #include "2dphysics.h"
 #include "sprite.h"
+#include "anim.h"
 
 #include "yugine.h"
 
@@ -391,6 +392,73 @@ s7_pointer s7_int_cmd(s7_scheme *sc, s7_pointer args) {
     }
 }
 
+s7_pointer s7_yield(s7_scheme *sc, s7_pointer args) {
+    /* arg 1: condition
+         arg 2: function  to run
+    */
+
+
+    s7_pointer cond = s7_car(args);
+    s7_pointer func = s7_cadr(args);
+
+
+}
+
+void timer_s7_call(s7_pointer sym) {
+    s7_call(s7, sym, s7_nil(s7));
+}
+
+s7_pointer s7_timer(s7_scheme *sc, s7_pointer args) {
+    double delay = s7_real(s7_car(args));
+    s7_pointer sym = s7_cadr(args);
+
+    struct timer *timer = timer_make(delay, timer_s7_call, sym);
+    timer_start(timer);
+    return args;
+}
+
+s7_pointer s7_timer_cmd(s7_scheme *sc, s7_pointer args) {
+    int cmd = s7_integer(s7_car(args));
+    int id = s7_integer(s7_cadr(args));
+
+    struct timer *t = NULL;
+
+    switch (cmd) {
+        case 0:
+            timer_pause(t);
+            break;
+        case 1:
+             timer_start(t);
+             break;
+         case 2:
+             timer_stop(t);
+             break;
+    }
+
+    return args;
+}
+
+s7_pointer s7_anim(s7_scheme *sc, s7_pointer args) {
+    s7_pointer prop = s7_car(args);
+    s7_pointer keyframes = s7_cadr(args);
+
+    YughInfo("Animating property %s.", s7_symbol_name(prop));
+
+    struct anim a = make_anim();
+
+    for (int i = 0; i < s7_list_length(sc, keyframes); i++) {
+        struct keyframe k;
+        s7_pointer kf = s7_list_ref(sc, keyframes, i);
+        k.time = s7_real(s7_car(kf));
+        k.val = s7_real(s7_cadr(kf));
+        a = anim_add_keyframe(a, k);
+    }
+
+    for (double i = 0; i < 3.0; i = i + 0.1) {
+        YughInfo("Val is now %f at time %f", anim_val(a, i), i);
+    }
+}
+
 #define S7_FUNC(NAME, ARGS) s7_define_function(s7, #NAME, s7_ ##NAME, ARGS, 0, 0, "")
 
 void ffi_load() {
@@ -424,5 +492,11 @@ void ffi_load() {
     S7_FUNC(int_cmd, 2);
 
     S7_FUNC(log, 4);
+
+    S7_FUNC(yield, 2);
+    S7_FUNC(timer, 2);
+    S7_FUNC(timer_cmd, 2);
+
+    S7_FUNC(anim, 2);
 }
 
diff --git a/source/engine/yugine.c b/source/engine/yugine.c
index a12c310..11f9bd2 100644
--- a/source/engine/yugine.c
+++ b/source/engine/yugine.c
@@ -44,6 +44,8 @@ static double lastTick;
 
 static float timescale = 1.f;
 
+static double framems;
+
 void seghandle(int sig) {
 #ifdef __linux__
     void *ents[512];
@@ -192,7 +194,6 @@ int main(int argc, char **args) {
             window_renderall();
         }
 
-
         double wait = fmax(0, renderMS-elapsed);
         input_poll(wait);
         window_all_handle_events();